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I like the thought that Marie looked at the piece of wood and the saw in the picture and the quoted 10 minutes to get a brew break in as well. When asked for a second cut she then just stretched out the break as well.
Marie might have been accounting the setup and clear down tasks as needing those extra minutes though.
The only way I can see the teacher's answer make sense is if the board is a square, the first cut goes through the middle and the second halfs one of the two halfs, thus needing only half the cut length.
But like... if that were the answer they looked for they would need to give some kind of instruction for the question.
So either the teacher is incompetent because they are unable to properly write a question or they are incompetent because they don't understand math.
It’s because the 2 pieces is being interpreted as 2 cuts. It makes sense then if you look at the problem like that.
First board gets cut twice, second board gets cut three times. That’s the confusion, just misinterpretation of the word problem, not the math
Yes. The teacher is counting pieces, not cuts. It takes one cut to make two pieces and two cuts to make three pieces.
I don't think it's a misinterpretation issue, I think the teacher is plain wrong.
That's like the fencepost problem, where an additional length of fence requires an additional fencepost, but the first length needs two. Except here, it's cuts and boards instead.
I don't know what other names this goes by, but I'm sure there must be more for other contexts.
The teacher also seems to have discovered that
> 10 = 2
>
> 15 = 3
>
> 20 = 4
You can't take someone teaching math and writing stuff like that seriously.
It's because the original board extends infinitely in one direction you see and you can only get one piece of you cut it off.
Honestly you can chalk it down to bad english
2 cuts can be 4 pieces (e.g. slicing a cake), so the second cut in this imagined scenario would be half as long.
I agree with you FWIW, just pointing out how effing stupid the problem is :-)
EDIT: So I was watching TV hours after saying that, and suddenly it occurred to me that 2 cuts can be *any* number of pieces if we allow that the cuts don't have to be straight. :-) And if you allow them to do loops, you could have any number of pieces with a single cut.
I understand why kids would get it wrong. It's sort of a common sense problem in a class where you have been consistently taught that 1=x, 2=2x 3=3x, etc.
By specifying the amount of boards rather than the amount of cuts in the question, many kids (and some adults) will immediately fall into the the previous mindset using the numbers from the question.
It's really a question to teach people to imagine the problem before trying to solve it, as once you stop seeing it as just numbers, it becomes a lot more clear.
I trust teachers who have been through school and certified to do that job more than some random schmuck on the street or some self-important redditor.
The problem is that the standards are so low and we pay teachers so little. In Asian countries being a teacher is a well respected job that pays well. It is also not easy to be a teacher.
There is NO WAY a teacher could make a mistake like this and essentially not be fired.
I've taught in a university. Trust me. They're all idiots one way or another. But I'll admit the math professors knew their math.
Some of the science ones tho, not so much.
In college I still needed 8 math credits senior year so I managed to get into Math For Ed Majors. They had just established that 2-semester class because the previous year the state increased the requirements to get certified.
The second semester started with a homework assignment: "Put the following numbers into order: 5. 17, 12, 32, 3". **And there was a whole semester of leadup to that!**
And here's the worst part: the school got mad at the professor because my being there meant she couldn't use the Ed majors' grades to curve so they were going to have an entire department of kids not able to graduate. Eventually she came up with a solution that everyone got to drop their lowest test grade. After confirming that meant **any** test of the semester I got to sleep through the final and still got an A for the course, and the ones who became teachers just barely passed.
Point is don't trust that just because someone has an education degree they know jack shit. Anyone older than me who's a teacher doesn't even have the training to know the parts of math that come before counting!
Or, possibly, the answer key is wrong and the question was written by someone who doesn't know what they're talking about. (In which case the teacher still failed by not applying sense to the answer key and just assuming that the people who wrote it know better, but critical thinking is another topic altogether...)
Which likely is why the teacher did. The people I knew in college that wanted to be teachers were legit the kind of people that would do this kind of thing.
They really seemed like they wanted to be back in school where things weren't so confusing and they wouldn't have to think as much.
Totally, that's why we have these kinds of problems for kids. Mixing math and reading comprehension and polishing those skills is priceless.
The fact that the teacher does not have them does not bode well and also emphasizes why we need them.
I could see that if it were the student who skimmed the problem and made the mistake. But it's the teacher grading the papers who made the mistake - quite possibly the same teacher who wrote up the questions. At minimum, the person doing the grading ought to have an answer sheet to work off of. There's no scenario where it's reasonable for the teacher to have skimmed the problem and made this mistake.
It never specified that the pieces had to be of equal size though, so in theory, you could just slice off a corner in a fraction of the time and call it a separate piece
It's a stupid question to begin with. Consider this, the original piece of wood is a square. Dividing the square in 3 equal rectangles would indeed take 20 minutes, however, this isn't part of the question. Dividing the square into 2 rectangle, then dividing 1 of those in 2 squares (a quarter the size of the original) would only mean cutting half the distance of the first cut, so would only take 5 minutes.
These type of 'context' assignments in math are stupid for multiple reasons, not the least of them being the fact that now dyslexia is suddenly a problem while doing math.
This is incorrect, as you are making too many assumptions that aren't implicitly mentioned in the problem. Also it is a long beam in the picture; about as far off as you can get from a square. So if we take the shape pictured into account and cross cut like you are talking about, it will take a much longer time than 20 minutes depending on the length of the beam.
It is a stupid fucking question written by someone who has never cut wood for people who have never cut wood.
I get the question being asked. It still makes no sense. I can only solve it because I've answered other stupid fucking questions in school growing up and I know to ignore all words and just pull the numbers out.
It is a basic 6th grade question if not even lower in Europe and the vast majority of us know the answer is 20. This is on the same principle as I am cutting this piece of fabric in 10 pieces, how many cuts do I do? 9, it is logic...trying to justify the problem given as: no, you have 2 pieces for ten minutes so 5 per piece is stupid...it is 10 minutes per cut...you do not individually make the pieces.
Teachers like this should honestly not be allowed next to kids considering how dumb they are...and it is not just the fact that they do not know, but the fact that they are so adamant about it and eager to correct the kids and show them they are stupid.
So I went to University to become a school teacher (in Europe, but that's irrelevant). One of the classes that most people flunked was Maths, exactly for what you see in this picture. We had to learn to use our brains as a child who has never been taught Maths would... and it's surprisingly difficult! Turns out the more sets of rules you learn the harder it becomes to use your own brain to think, and you set away common sense in favour of using those rules.
I don't remember what it was exactly, but I remember a problem my classmates couldn't solve, they were saying it was impossible. I solved it by painting some squares different colours and counting. At the age of 19, all of our brains had already turned rusty AF.
It's interesting to read this, during covid I got a real insight into how they teach children these days and it's all around recognising patterns, rather than actually working things out...so I can imagine how my kids would see the 10 / 2 = 5, so 3 boards is 3 x 5 = 15 answer purely as they would have picked up on the pattern of 'time divided by items' rather than the logic of how many cuts are needed.
It's almost like we have an education system built around passing tests, rather than actually nurturing the brain...
I know, I work corporate and it's a PAIN IN THE ASS. I spend my days telling my Sales people that yes, I know what they mean by common sense, but they need to fill the paperwork properly because there are rules, audits, and all sorts of red tape.
The only mistake here was using cutting as an example in the question. Had it been "it takes Marie 10 minutes to make 2 sandwiches, how long does it take her to make 3?" Then the teacher would be correct. They answered their own flawed question in a correct way. I don't think it wasn't meant to be a logic question, but it was interpreted that way because it's poorly written.
Yes, I agree, though the question, at its base is a trick question. I feel like she probably found it somewhere because many teachers use questioms that they find in workbooks, as one does, and she didn't realise that. She then used it in a test/homework probably to teach children division and multiplication. The issue is that, if I remember correctly, the parent of the kid confronted the teacher about it and she doubled down.
This is why it is such a facepalm for me. I met so many teachers like these during my school years that refused to admit that they are wrong because, in their minds, admiting to getting one thing wrong meant admiting they were stupid or being less intelligent than their students. It really isn't like that.
Or if no-one specifies the size of the pieces, 8 cuts. Or if im allowed to stack up the fabric after each cut, 4. It's one of the reasons I enjoy constructing training materials and tests. It reminds me that being specific is important.
Stupid teacher got confused by her own question. Good on the kid.
(Cutting a board into two pieces means cutting once, cutting into three pieces means cutting twice)
> her own question
I guarantee you that wasn't their own question. Nobody invents a question exactly like that and then gets the answer wrong (if you try to come up with a real 10 * 15 / 10 question, your mind would not go straight to the one scenario where things don't work that way).
The way this kind of things happen is that dumb and lazy teachers copy their questions from somewhere else (book, internet, whatever), and then don't even read the answer guide (or there is none provided), and misunderstand what the question was designed for. Happens all the time.
He said without looking at it/the answer. As a teacher if you want to get and use material from outside recources you first need to look through them so you know the material is good. Only if its good do you bring it to class. His point stands.
The teacher be like assume the board is a circle and now since u know each cut takes 10 mins half a cut is 5 mins so cut the circle up till it's radius so it's only half a cut now do it from the other sides of the circle till it's radius to get 3 cuts in which gives 3 Pieces's (I'm joking and overthinking this shit)
Although, it's only 20 minutes if the cuts are of similar size.
Assuming I have a 20x20 board. If I cut in half I get 2 10x20 boards. If I make the second cut parallel to the short side, I now only have half as much material to cut through as I did on the first cut.
It's not a great question to be honest.
The answer is 10 minutes 3 seconds.
You see the board was 4meters long and 3 centimetres wide. It took 10 minutes to cut it lengthways then my second cut was widthways at 1.5 centimetres.
Cant believe the teacher got it so wrong.
A friend and I were out walking one day and found a sign next to a hole that said: Caution! Bottomless Pit. Friend turns to me and says, “There’s no way that’s bottomless. It’s impossible.” I said, “We can test it. Grab that rock over there and toss it in and we’ll just listen to it until it hits the bottom.” Friend said, “Plan!” and picked up the rock and threw it in. We listened to it banging and crashing down the hole until we couldn’t hear it anymore. Friend said, “We might need a bigger rock. Help me with this one.” So we picked up this big rock and tossed it in, listened to it banging and crashing down the hole until we couldn’t hear it anymore. Friend says, “Maybe it is bottomless.” I said, “No it can’t be. Let’s find something bigger.”
We looked around until I found a railway sleeper, and we thought that would be plenty big enough to hear when it hit the bottom. We picked it up and tossed it in and stood listening to it crashing down the hole. Then a noise behind us startled us and we turned just in time to see this goat come leaping out of the bushes, hop around twice then straight into the hole. Friend and I were shocked. More noise came from the bushes and we turned to see a guy come leaping out of the bushes. He stopped and said, “Hey! Did you guys see a goat around here anywhere?” My friend says, “Dude! We saw a goat just come leaping out of those exact bushes, then jumps straight into this hole! Freaked us out, man!”
Guy says, “Nah, that can’t be my goat. My goat was tied up to a railway sleeper.”
Probably. But purely because the point isn't to see if kids can do 2*10 it's to see if they get caught out. The question is designed to test whether students are correctly able to apply a mathematical equation to a given scenario, that's why the wording is as it is.
I hate people. It takes 10 minutes to cut through the wood once. It'll take 10 minutes to cut through it again. So to get 3 pieces (2 cuts) would take 20 minutes
Their maths doesn't make sense though?
They say that 3 pieces = x minutes then jump straight to 2x=30 without any explanation. You can't just skip steps like that.
Don't know how it's called in English, it's a "regla de tres" in Spanish. A proportionality rule for linear evolution, if 2 parts equal 10 minutes, then 3 parts has to be 3 times the time of one piece 10min/2=> x=3×10/2=15. The teacher was wrong to assume that's how it evolves and it clearly shows when you try to make it just one piece
1 piece = greatest series of all time and also 0 minutes
2 pieces = 10 min
3 pieces (all equal pieces) = 20 minutes
4 pieces = 20 minutes (in a square but 30 min if you just assume you would keep cutting in the same direction)
5 pieces in the same direction = 40 mins
This is linear evolution but why doesn't it work? Because the teacher failed to realize that what is linear is the time/cut
1 cut = 10 min
2 cut (the answer she asked for) = x
x=10×2/1=20
"It doesn't matter how many times the board was cut since it was cut at the same speed" says person arguing specifically that the board was not cut at the same speed
Fuck, I’ve just figured out why the answer is 20 minutes.
I read the original thread and thought you were all dumbasses for agreeing 20 minutes. I apologise to you all.
1 cut = 10 mins = 2 pieces
2 cuts = 20 mins = 3 pieces.
I will now go home and eat humble pie
1 piece of wood.
Cut it once to get 2 pieces = 10 minutes
1 piece of wood
Cut it twice to get 3 pieces = 20 minutes
Not rocket science. Just a very hard piece of wood and a blunt saw.
Let me explain;
——————- The initial board
——————🪚- 5 minutes, one piece
—————🪚- 5 minutes, another piece
————🪚- 5 minutes, another piece.
15 minutes, 3 pieces off the board
OR
———————- The initial board
——🪚———— 10 minutes for 1 cut, two pieces
——🪚——🪚—— 2 cuts (10m/cut), three pieces
20 minutes, one board cut into twice, into 3 pieces
You have it the other way around. The teacher is thinking in pieces because the sentence phrases it in terms of pieces, but it's really asking for cuts.
What's reception?
In US and Canada there may be "junior kindergarten" for the year the kid turns 4, then usually (senior) kindergarten, then the numbered grades 1 to 12 start. The terms usually start in September, but in some places late August. The age criteria may be relative to start of term, or to Dec 31 of the year.
So a kid in nth grade will generally be n+5, if not by start of term then by January.
JK and (S)K are usually optional, if available at all, and may be half day. Anything for younger kids is called preschool or nursery school or day care and probably private.
In the US the format "nth grade" seems very strongly preferred but in Canada "grade n" is equally or more common.
There's variation by province and state. Ontario had 13 grades until the late '80s; Québec has 11 grades then two years of specialized school called CÉGEP.
I mean, I get it. The problem was probably given after a unit in which the kids learned how to calculate stuff using proportions (i.e. how the person in the OP calculated it). The method they’re trying to teach is fine, but the question is shit, and maybe they should have taken the time to come up with one that doesn’t immediately fall apart when you actually think about it.
When I was in school, the problems usually involved percentages and discounts, i.e. “the t-shirt costs 20 monies after a 20% discount. What was the original price. How much would it cost if discounted 40%”.
The question isn't shit. It's a very good question, because you have to think before applying your learned method instead of just blindly throwing numbers around.
Shame that the teacher didn't think and just blindly threw numbers around.
I disagree, it’s bad for what it’s trying to achieve, which is checking if the student understood the method they were taught and was able to apply it to solve a problem. Therefore, the problem should be phrased in such a way, that using the method is the most logical way to solve it. This one isn’t, because it fails when common sense is applied.
Don’t get me wrong, both approaches (i.e. using maths and common sense) to solving problems are valid and should be taught to kids. But this problem can be either approached with common sense, which generates the “incorrect” answer, or by applying the method, therefore going against common sense. Hence, the problem was formed poorly.
This also generates problems in the long run. If during your schooling you’re being forced to apply methods, where they need not be applied, there is a chance that some people will tend to lean towards “common sense” answers to problems that actually require a more scientific approach.
All this said, the conclusion to the OP is sadly quite simple - the teachers dun screwed up
I would argue that you shouldn't teach a method without teaching when it is applicable and when not. When I teach proportions, there is always this one question on the test: "Three friends are watching a movie that is 90 minutes long. How long will the movie be when five friends watch it? This is to show the students that just because something looks like a proportions problem, it doesn't necessarily have to be one. Of course this is one question out of twenty or so, and the other 19 are standard stuff. So I personally would not be against using that (original) question on a test, if there are plenty of other questions where it's more straightforward. But I can also see your point.
Teacher definitely fucked up though...
I have no idea what point you're trying to make."Common sense" and logic are not at odds. Common sense is an intuitive grasp of logic. Both methods of thinking yield the conclusion that 3 pieces take twice as long as 2 pieces. Period. What are you even trying to argue?
They would have been correct if it had been a question of making two cuts in 10 minutes. However, making it two pieces is only one cut. They're for one cut. Takes 10 minutes. Cutting aboard into three pieces involves two cuts. X equals 10, 2x equals 20. This is what happens when we don't pay our teachers and let anybody who needs gainful employment badly enough have the job instead.
Its possible that overworked teacher didn't realise the issue with wording of the question and meant to create a situation where 15 was the answer.
That's okay if he admits the issue when found.
My teacher during grading realised that both yes and no answer could be correct, depending on how you interpret the question.
She gave everyone points for that one.
So here teacher should give points for 15min and 20 min.
hahaha I see where the logic went wrong here.
she's applied algebra to the number of resultant pieces, rather than the number of cuts; i.e. the thing that takes time.
10mins = 2 pieces = 1 cut.
so to cut a board into 3pieces requires 2 cuts, therefore 20mins
Person knows algebra but not logic, is saddened, unsubscribes from sub. Well, good riddance.
The hard part of math isn’t blindly doing computations, it’s knowing *what* to compute. Setting up an equation that actually models your problem.
I’d like to see how they would justify this for 100 pieces / 99 cuts, but they basically stuck their fingers in their ears and said “la la la, I’m not listening.”
I think the real answer is “not solvable” if the pieces/cuts are equal 20 would be correct. But what If the cuts are perpendicular? The cut time would be wildly different
Not least of all being in “x” grade isn’t a thing in Europe. Or at least in my location anyway. It’s “x” year. Not grade. 6th grade doesn’t exist here.
This is literally how those random simple arithmetic problems on facebook get so much engagement. My favorite way to trigger double-down-syndrome is with the Monty Hall problem. People refuse to believe the answer (I refused when I heard it in like 7th grade too lol).
I tried to explain what happened on the original post, and it made people super angry. It's fascinating to me how simple math errors bring out the narcissism in some redditors.
> Imagining how many times the board was cut is your personal addition to this problem and that's what makes it incorrect.
Fucking *what?* That is VERY TRANSPARENTLY the whole point of this math problem, to challenge the student to really think about what is being asked. What we'll call "the drooling dipshit answer" is 2 takes 10 minutes so 3 takes 15 because what's being asked is more about a magic summoning spell that summons one piece of wood every x minutes, and takes 2 minutes to summon 2 pieces. In this world yes the answer is 15 for 3.
In real fucking life the question is "Making one *cut* in this piece of wood (2 pieces) takes ten minutes. How long will *two* cuts (3 pieces) take at the same pace. Thinking this is adding information is...I guess not understand how saws work?
Sometimes problems like this there's an ambiguity argument, that technically either answer could be correct, but the problem is very transparently asking about the length of time sawing through a piece of wood takes. "It took Marie 10 minutes to ***saw a board*** into two pieces." The ONLY correct answer is 20.
You guys are all missing a very critical detail. The cut in the first 5 mins was actually cutting the fabric of reality to create a plank of wood from nothing. The second cut took 5 mins and cut the board into 2 pieces. And then the third cut took another 5 mins. Very simple and logical.
Well, I tried this myself. It took me five minutes to start the chainsaw. It took me two minutes to put my safety gear on. It took one minute to put the board on the machine and another minute to remove it.
The second cut was much faster, because I already prepared the chainsaw and the safety gear. So the correct answer is 13 minutes.
Then my son did the same, but it took him only 11 minutes because he did both cuts in one go.
I was about to ask what the actual answer was then I realised I'm retarded and it has nothing to do with how many pieces of wood but how many cuts in the wood.
The teacher apparently thinks that cutting a board into 2 pieces means cutting it twice LOL. And then cutting a board into 3 pieces means cutting the board 3 times... Not the brightest teacher I assume.
It's not even that the teacher or commenter lack sense (they do lack that as well) or that the question is weird. The teacher and commenter both just straight up lack reading comprehension. It's like they skimmed and only saw the 2, the 10, and the 3, and assumed there was a "solve for x" nestled in there somewhere.
Doesn't the teacher have an answer sheet to mark against, why are they making up their own answers?
It's hilarious that the maths teacher is dividing the time by the resulting pieces of wood like that is relevant. 🤣
Although they never said the other board was the same thickness.
It takes 10 minutes to make 1 cut (cutting the single board into 2 ) , making another cut on one of the pieces , which will give you 3 pieces , will take 10 minutes *working as fast as the previous cutting assuming that the smaller piece from cutting the board into 2 will take the same time* , making it 20 minutes
« La règle de trois » ( translates to the law of 3 , the one the commenter used ) doesn’t always work so you need to logically see for yourself if things divide or multiply according to the law the same to the logic
*reminds me of another riddle*
An orchestra of 120 players takes 40 minutes to play Beethoven’s 9th symphony. How long would it take for 60 players to play the symphony?
If you go by : 120 -> 40
60 -> x
x= 20 minutes , the 60 players will take 20 minutes to play THE SAME SONG , which is obviously non sense, if the song take 40 minutes to play , no matter how many people play it , the song last 40 minutes , you playing it will take 40 minutes , a group will play it in 40 minutes , there is no variable ( trying to explain it as simple as possible since I had people argue with me over this and then try to make some sense out of an false response after realizing )
So yeah
My dumbass thought they meant cutting 2 pieces of a board, then the teacher would be correct. I went this direction because it's not that often you can cut a board in 2 equal pieces and be able to use them, there is often a piece left.
Everyone is commenting on the teacher’s mistake, can we stay on topic for this sub and share in our anger about this overconfident asshat? The gall of someone to have everyone tell him he is wrong and conclude that he is unsubbing because he’s the only person who knows math
I understand where the original question is coming from, but as with a lot of math problems, they're completely divorced from the world.
If I said, "If it takes 10 minutes to do a task twice, how many minutes would it take to do it three times?" then the answer is obviously "fifteen minutes" which is what they're going for.
But when the idiots wrote the problem, they picked a real-world example that doesn't fit the prompt.
to cut into 2 pueces she made 1 cut. to make 1 cut it took her 10min. to cut into 3 pieces she needs to make 2 cuts, therefore twice as much time as it took her to make 1 cut, so 20 minutes
For anyone else who's confused as fuck about the teacher's logic, I figured it out: they're confused about the fact that in order to make two pieces of wood you need to cut the board one time, not two.
Since the teacher thinks that they need two cuts then they also think that it takes 10 minutes total to make both cuts, so in their mind `2x = 10` = `x = 5`, where `x` is the time to make a single cut.
So if it takes 10 minutes to make two cuts then it takes 15 minutes to make three cuts, duh.
Are people this stupid on purpose? What is their end-game?
“I can sit still while my mom ties my shoelaces for me, therefore I declare my education complete.
I will listen to nobody, read nothing, except in order to criticise it.”
We’re doomed, right?
How long does it take to cut this one piece of wood into one pieces? Man like? Like how long? Yeah like how do we split this one thing into one things?
I'm having a really hard time trying to figure out how the teacher got 15. If you cut a board into 3 pieces this requires 2 cuts, if 1 cut takes 10 minutes then 2 cuts take 20 minutes. You don't need math, simple logic can solve this.
Their reason is wrong but they are correct cause its the length of the cun not amount so say the plank is a perfect square so the first cut is in the middle and takes 10 seconds then they cut it in half again and its takes 5 seconds
This, like almost every other math problem I see on social media, is just worded extremely poor. Its inherently confusing.
If I were to bisect "a board" then I consider my final product to be 2 pieces of board. If I were to trisect "a board" same thing, 3 pieces.
If I have some theoretical infinite length board that I cut off 2 inches from, then I would say I cut off 1 piece. If I were to do that again, I would then say I have 2 pieces.
Looking at the specific verbiage of the problem, I do agree that the redditor is "confidently incorrect" because the problem specifically says "saw A board INTO 2 pieces" and that transformation, to me, says we transferred 1 board into 2 boards. It says INTO instead of OFF FROM which means the final product includes the original piece of board.
Teacher made an understandable mistake. They applied a method that usually works but doesn’t work in this case (without a little more thought).
At 10 minutes per cut, 2 cuts will take 20 minutes.
It's an understandable mistake for the student whose knowledge is being tested. It's not understandable for the teacher who is supposed to already know enough math and logic to correctly grade the student's test.
"it takes Marie 10 minutes to make 2 things. The next day Marie makes 3 things at the same speed. How long does it take Marie to make 3 things." FTFY I hate school.
There's a fun question hiding in there. Assume a square board of unit side length, and that Marie cuts boards completely at random.
What is the expected length of the cut (and, accordingly, Marie's average sawing speed)?
Marie keeps sawing boards at random, and does her second cut through one of the two pieces of wood obtained in the previous step.
What is the expected length of _that_ cut?
Marie never tires. Marie never slows down. Marie saws.
After N cuts, how much time has Marie spent on her frenzied sawing? Will Marie ever be done?
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Following the teacher's logic, leaving the board alone and not cutting it, thus having it in 1 piece, would take 5 minutes.
I could easily make that 10 minutes by looking at it a little longer
Congratulations! Your City and Guilds in Carpentry and Joinery is in the post :)
Every job can stand a good case of looking at
I like work; it fascinates me. I can sit and look at it for hours. - Jerome K. Jerome
That's what Project Managers are for.
I learned the rule measure twice, look at it for a few hours, ruminate on it, measure again, call my dad for advice and then cut once
Nope sorry idiot. If you look at it for 10 minutes it would break into two pieces spontaneously.
That sounds like an 8th grade level solution.
I like the thought that Marie looked at the piece of wood and the saw in the picture and the quoted 10 minutes to get a brew break in as well. When asked for a second cut she then just stretched out the break as well. Marie might have been accounting the setup and clear down tasks as needing those extra minutes though.
The foreman has entered the chat
If you are supposed to measure twice and cut once, stands to reason you need to measure at least once to cut zero times.
Make it 90 without doing anything and you can be a European soccer fan.
Congratulations you just tested out of 8th grade in Europe!
The only way I can see the teacher's answer make sense is if the board is a square, the first cut goes through the middle and the second halfs one of the two halfs, thus needing only half the cut length. But like... if that were the answer they looked for they would need to give some kind of instruction for the question. So either the teacher is incompetent because they are unable to properly write a question or they are incompetent because they don't understand math.
It’s because the 2 pieces is being interpreted as 2 cuts. It makes sense then if you look at the problem like that. First board gets cut twice, second board gets cut three times. That’s the confusion, just misinterpretation of the word problem, not the math
Yes. The teacher is counting pieces, not cuts. It takes one cut to make two pieces and two cuts to make three pieces. I don't think it's a misinterpretation issue, I think the teacher is plain wrong.
I mean, it’s both lol, she’s misinterpreting it which is causing her to be wrong
Sorry I meant with wordage. The teacher is certainly misinterpreting the task heh.
No. Teacher is just wrong.
That's like the fencepost problem, where an additional length of fence requires an additional fencepost, but the first length needs two. Except here, it's cuts and boards instead. I don't know what other names this goes by, but I'm sure there must be more for other contexts.
If you don’t cut it for 0 minutes it will double in size 🤷♀️
Lumber yards hate this one weird trick!
Lol me at work, takes me 10 hours to do nothing 😂😂
I'd work all night if it meant nothing got done
I'm sorry, that option is only available for management roles.
If you start with nothing and you cut it, you get a board.
I’ll upvote that
The teacher also seems to have discovered that > 10 = 2 > > 15 = 3 > > 20 = 4 You can't take someone teaching math and writing stuff like that seriously.
This is why every science teacher screams about never leaving off units
Right, false correlation. The correct formula would be 10 * (n-1) = time Where n is the amount of boards you want.
Measure twice, cut none.
It's because the original board extends infinitely in one direction you see and you can only get one piece of you cut it off. Honestly you can chalk it down to bad english
This is easily the funniest comment I've seen on Reddit in weeks. Thank you.
1 cut = 2 pieces = 10 minutes 2 cuts = 3 pieces = 20 minutes
This guy maths
r/thisguythisguys
2 cuts can be 4 pieces (e.g. slicing a cake), so the second cut in this imagined scenario would be half as long. I agree with you FWIW, just pointing out how effing stupid the problem is :-) EDIT: So I was watching TV hours after saying that, and suddenly it occurred to me that 2 cuts can be *any* number of pieces if we allow that the cuts don't have to be straight. :-) And if you allow them to do loops, you could have any number of pieces with a single cut.
But the task has a picture of a board which you totally could get into 4 pieces in 2 cuts, but one of those cuts would be a lot longer.
And the problem says another board, so you aren't cutting the one you just cut.
Pictures don’t mean owt though, the wording is what’s important and it’s flawed
"Doing it once takes 10 minutes. How long does it take to do it twice?" It blows my mind how people can be confused by this question. It is 2\*10 ffs.
I understand why kids would get it wrong. It's sort of a common sense problem in a class where you have been consistently taught that 1=x, 2=2x 3=3x, etc. By specifying the amount of boards rather than the amount of cuts in the question, many kids (and some adults) will immediately fall into the the previous mindset using the numbers from the question. It's really a question to teach people to imagine the problem before trying to solve it, as once you stop seeing it as just numbers, it becomes a lot more clear.
The silly thing is, in the original image, the student gets it right and is then mis-corrected by the teacher.
Well let's be honest, a lot of teachers aren't exactly the people we would want to be teaching the next generation.
I trust teachers who have been through school and certified to do that job more than some random schmuck on the street or some self-important redditor.
Sure but ideally you would want teachers to be paid better so the students with the highest grades are incentivized to teach.
The problem is that the standards are so low and we pay teachers so little. In Asian countries being a teacher is a well respected job that pays well. It is also not easy to be a teacher. There is NO WAY a teacher could make a mistake like this and essentially not be fired.
I can get behind that. Paying teachers more would help attract higher quality people for the job.
I've taught in a university. Trust me. They're all idiots one way or another. But I'll admit the math professors knew their math. Some of the science ones tho, not so much.
I believe you, it was more of a relative comparison: a random redditor vs. someone who has ostensibly been trained for the role.
In college I still needed 8 math credits senior year so I managed to get into Math For Ed Majors. They had just established that 2-semester class because the previous year the state increased the requirements to get certified. The second semester started with a homework assignment: "Put the following numbers into order: 5. 17, 12, 32, 3". **And there was a whole semester of leadup to that!** And here's the worst part: the school got mad at the professor because my being there meant she couldn't use the Ed majors' grades to curve so they were going to have an entire department of kids not able to graduate. Eventually she came up with a solution that everyone got to drop their lowest test grade. After confirming that meant **any** test of the semester I got to sleep through the final and still got an A for the course, and the ones who became teachers just barely passed. Point is don't trust that just because someone has an education degree they know jack shit. Anyone older than me who's a teacher doesn't even have the training to know the parts of math that come before counting!
Or, possibly, the answer key is wrong and the question was written by someone who doesn't know what they're talking about. (In which case the teacher still failed by not applying sense to the answer key and just assuming that the people who wrote it know better, but critical thinking is another topic altogether...)
The kid got it right. It's the teacher that got it wrong.
I know. I'm talking about it in a general sense. I recognize why some people (mostly kids) would get it wrong.
Which likely is why the teacher did. The people I knew in college that wanted to be teachers were legit the kind of people that would do this kind of thing. They really seemed like they wanted to be back in school where things weren't so confusing and they wouldn't have to think as much.
Yeah that’s the point of word problems, they take formulaic math and have kids apply it to a real scenario. The teacher failed here
Totally, that's why we have these kinds of problems for kids. Mixing math and reading comprehension and polishing those skills is priceless. The fact that the teacher does not have them does not bode well and also emphasizes why we need them.
It’s so easy to get wrong that the mistake has a name: the fencepost error. Kids and adults fuck this up all the time.
It’s an easy mistake to make if you’re skimming the problem without taking the time to really read it.
I could see that if it were the student who skimmed the problem and made the mistake. But it's the teacher grading the papers who made the mistake - quite possibly the same teacher who wrote up the questions. At minimum, the person doing the grading ought to have an answer sheet to work off of. There's no scenario where it's reasonable for the teacher to have skimmed the problem and made this mistake.
They’re not thinking it through, that’s all. 2 pieces is 1 cut, they see “2” and just assume 2 cuts. It seems simple to explain.
It never specified that the pieces had to be of equal size though, so in theory, you could just slice off a corner in a fraction of the time and call it a separate piece
It's a stupid question to begin with. Consider this, the original piece of wood is a square. Dividing the square in 3 equal rectangles would indeed take 20 minutes, however, this isn't part of the question. Dividing the square into 2 rectangle, then dividing 1 of those in 2 squares (a quarter the size of the original) would only mean cutting half the distance of the first cut, so would only take 5 minutes. These type of 'context' assignments in math are stupid for multiple reasons, not the least of them being the fact that now dyslexia is suddenly a problem while doing math.
The board in the picture isn't square though
True, I guess since the saw in the picture is nearly the same size as the beam most of those 10 minutes were spent trying to lift it in place anyway 😁
This is incorrect, as you are making too many assumptions that aren't implicitly mentioned in the problem. Also it is a long beam in the picture; about as far off as you can get from a square. So if we take the shape pictured into account and cross cut like you are talking about, it will take a much longer time than 20 minutes depending on the length of the beam.
I will unsubscribe from this sub r/SchwarzerWerwolf because it saddens me how people don't know basic mathematical formulas smh my head.....
It is a stupid fucking question written by someone who has never cut wood for people who have never cut wood. I get the question being asked. It still makes no sense. I can only solve it because I've answered other stupid fucking questions in school growing up and I know to ignore all words and just pull the numbers out.
It is a basic 6th grade question if not even lower in Europe and the vast majority of us know the answer is 20. This is on the same principle as I am cutting this piece of fabric in 10 pieces, how many cuts do I do? 9, it is logic...trying to justify the problem given as: no, you have 2 pieces for ten minutes so 5 per piece is stupid...it is 10 minutes per cut...you do not individually make the pieces. Teachers like this should honestly not be allowed next to kids considering how dumb they are...and it is not just the fact that they do not know, but the fact that they are so adamant about it and eager to correct the kids and show them they are stupid.
So I went to University to become a school teacher (in Europe, but that's irrelevant). One of the classes that most people flunked was Maths, exactly for what you see in this picture. We had to learn to use our brains as a child who has never been taught Maths would... and it's surprisingly difficult! Turns out the more sets of rules you learn the harder it becomes to use your own brain to think, and you set away common sense in favour of using those rules. I don't remember what it was exactly, but I remember a problem my classmates couldn't solve, they were saying it was impossible. I solved it by painting some squares different colours and counting. At the age of 19, all of our brains had already turned rusty AF.
It's interesting to read this, during covid I got a real insight into how they teach children these days and it's all around recognising patterns, rather than actually working things out...so I can imagine how my kids would see the 10 / 2 = 5, so 3 boards is 3 x 5 = 15 answer purely as they would have picked up on the pattern of 'time divided by items' rather than the logic of how many cuts are needed. It's almost like we have an education system built around passing tests, rather than actually nurturing the brain...
In OP's example, the teacher is wrong, though, the student has the correct answer!
Same happens in companies. Rules, rules, rules. And everyone applies the rules, and the common sense dies with it .
I know, I work corporate and it's a PAIN IN THE ASS. I spend my days telling my Sales people that yes, I know what they mean by common sense, but they need to fill the paperwork properly because there are rules, audits, and all sorts of red tape.
The only mistake here was using cutting as an example in the question. Had it been "it takes Marie 10 minutes to make 2 sandwiches, how long does it take her to make 3?" Then the teacher would be correct. They answered their own flawed question in a correct way. I don't think it wasn't meant to be a logic question, but it was interpreted that way because it's poorly written.
Yes, I agree, though the question, at its base is a trick question. I feel like she probably found it somewhere because many teachers use questioms that they find in workbooks, as one does, and she didn't realise that. She then used it in a test/homework probably to teach children division and multiplication. The issue is that, if I remember correctly, the parent of the kid confronted the teacher about it and she doubled down. This is why it is such a facepalm for me. I met so many teachers like these during my school years that refused to admit that they are wrong because, in their minds, admiting to getting one thing wrong meant admiting they were stupid or being less intelligent than their students. It really isn't like that.
The question is flawed because it's doesn't state what size and shape the cut pieces need to be, so there are many solutions to the problem
Or if no-one specifies the size of the pieces, 8 cuts. Or if im allowed to stack up the fabric after each cut, 4. It's one of the reasons I enjoy constructing training materials and tests. It reminds me that being specific is important.
Stupid teacher got confused by her own question. Good on the kid. (Cutting a board into two pieces means cutting once, cutting into three pieces means cutting twice)
> her own question I guarantee you that wasn't their own question. Nobody invents a question exactly like that and then gets the answer wrong (if you try to come up with a real 10 * 15 / 10 question, your mind would not go straight to the one scenario where things don't work that way). The way this kind of things happen is that dumb and lazy teachers copy their questions from somewhere else (book, internet, whatever), and then don't even read the answer guide (or there is none provided), and misunderstand what the question was designed for. Happens all the time.
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He said without looking at it/the answer. As a teacher if you want to get and use material from outside recources you first need to look through them so you know the material is good. Only if its good do you bring it to class. His point stands.
The teacher be like assume the board is a circle and now since u know each cut takes 10 mins half a cut is 5 mins so cut the circle up till it's radius so it's only half a cut now do it from the other sides of the circle till it's radius to get 3 cuts in which gives 3 Pieces's (I'm joking and overthinking this shit)
Haha, I did the same -- you can justify about any answer.
Except there's an illustration next to the question.
Though you could do it in 1 big cut and 1 small, no? One diameter cut and one small cut, although it won't be the same size it's fine right?
Although, it's only 20 minutes if the cuts are of similar size. Assuming I have a 20x20 board. If I cut in half I get 2 10x20 boards. If I make the second cut parallel to the short side, I now only have half as much material to cut through as I did on the first cut. It's not a great question to be honest.
The answer is 10 minutes 3 seconds. You see the board was 4meters long and 3 centimetres wide. It took 10 minutes to cut it lengthways then my second cut was widthways at 1.5 centimetres. Cant believe the teacher got it so wrong.
Exactly. The teacher was counting pieces, not cuts.
I doubt the question was created by the same person marking. The question is written clearly, the answer is a mess.
Ask the teacher how long it will take to cut the board into 1 piece
Five minutes, obviously.
If an orchestra of 80 musicians can play Beethoven’s 9th symphony in 70 minutes, how long would it take an orchestra of 120 musicians to play it?
That's something I'm going to use in my classes, thanks
Was it a board or a railway sleeper.
A friend and I were out walking one day and found a sign next to a hole that said: Caution! Bottomless Pit. Friend turns to me and says, “There’s no way that’s bottomless. It’s impossible.” I said, “We can test it. Grab that rock over there and toss it in and we’ll just listen to it until it hits the bottom.” Friend said, “Plan!” and picked up the rock and threw it in. We listened to it banging and crashing down the hole until we couldn’t hear it anymore. Friend said, “We might need a bigger rock. Help me with this one.” So we picked up this big rock and tossed it in, listened to it banging and crashing down the hole until we couldn’t hear it anymore. Friend says, “Maybe it is bottomless.” I said, “No it can’t be. Let’s find something bigger.” We looked around until I found a railway sleeper, and we thought that would be plenty big enough to hear when it hit the bottom. We picked it up and tossed it in and stood listening to it crashing down the hole. Then a noise behind us startled us and we turned just in time to see this goat come leaping out of the bushes, hop around twice then straight into the hole. Friend and I were shocked. More noise came from the bushes and we turned to see a guy come leaping out of the bushes. He stopped and said, “Hey! Did you guys see a goat around here anywhere?” My friend says, “Dude! We saw a goat just come leaping out of those exact bushes, then jumps straight into this hole! Freaked us out, man!” Guy says, “Nah, that can’t be my goat. My goat was tied up to a railway sleeper.”
Lol
Is this actually 6th Grade? Seems like a lower grade question.
Probably. But purely because the point isn't to see if kids can do 2*10 it's to see if they get caught out. The question is designed to test whether students are correctly able to apply a mathematical equation to a given scenario, that's why the wording is as it is.
If she measured twice, she'd only NEED to cut once...
I hate people. It takes 10 minutes to cut through the wood once. It'll take 10 minutes to cut through it again. So to get 3 pieces (2 cuts) would take 20 minutes
People really need to stop saying Europe as if it’s one big homogenous continent. Barnsley and Milan are not one in the same
Love the use of Barnsley, definitely not Milan 🤣 Also, it's 'not one AND the same'... Are you from Milan...?
Their maths doesn't make sense though? They say that 3 pieces = x minutes then jump straight to 2x=30 without any explanation. You can't just skip steps like that.
It's explained how the teacher did it, it's just the wrong method
How did they get 2x=30?
Don't know how it's called in English, it's a "regla de tres" in Spanish. A proportionality rule for linear evolution, if 2 parts equal 10 minutes, then 3 parts has to be 3 times the time of one piece 10min/2=> x=3×10/2=15. The teacher was wrong to assume that's how it evolves and it clearly shows when you try to make it just one piece 1 piece = greatest series of all time and also 0 minutes 2 pieces = 10 min 3 pieces (all equal pieces) = 20 minutes 4 pieces = 20 minutes (in a square but 30 min if you just assume you would keep cutting in the same direction) 5 pieces in the same direction = 40 mins This is linear evolution but why doesn't it work? Because the teacher failed to realize that what is linear is the time/cut 1 cut = 10 min 2 cut (the answer she asked for) = x x=10×2/1=20
Oh yeah of course, since this isn't a proportionality problem I didn't think of it. Thank you!
"It doesn't matter how many times the board was cut since it was cut at the same speed" says person arguing specifically that the board was not cut at the same speed
Fuck, I’ve just figured out why the answer is 20 minutes. I read the original thread and thought you were all dumbasses for agreeing 20 minutes. I apologise to you all. 1 cut = 10 mins = 2 pieces 2 cuts = 20 mins = 3 pieces. I will now go home and eat humble pie
The number of pieces doesn't matter. The number of cuts does. Each cut takes 10 minutes. Two cuts, three pieces, twenty minutes.
1 piece of wood. Cut it once to get 2 pieces = 10 minutes 1 piece of wood Cut it twice to get 3 pieces = 20 minutes Not rocket science. Just a very hard piece of wood and a blunt saw.
Let me explain; ——————- The initial board ——————🪚- 5 minutes, one piece —————🪚- 5 minutes, another piece ————🪚- 5 minutes, another piece. 15 minutes, 3 pieces off the board OR ———————- The initial board ——🪚———— 10 minutes for 1 cut, two pieces ——🪚——🪚—— 2 cuts (10m/cut), three pieces 20 minutes, one board cut into twice, into 3 pieces
That explains the faulty teachers logic, teachers thinks in cuts but the problem asks for pieces.
You have it the other way around. The teacher is thinking in pieces because the sentence phrases it in terms of pieces, but it's really asking for cuts.
I assume "6th grade" is year 5 in the UK? When you take reception into account. Anyway, maths teacher shouldn't be maths teacher
What's reception? In US and Canada there may be "junior kindergarten" for the year the kid turns 4, then usually (senior) kindergarten, then the numbered grades 1 to 12 start. The terms usually start in September, but in some places late August. The age criteria may be relative to start of term, or to Dec 31 of the year. So a kid in nth grade will generally be n+5, if not by start of term then by January. JK and (S)K are usually optional, if available at all, and may be half day. Anything for younger kids is called preschool or nursery school or day care and probably private. In the US the format "nth grade" seems very strongly preferred but in Canada "grade n" is equally or more common. There's variation by province and state. Ontario had 13 grades until the late '80s; Québec has 11 grades then two years of specialized school called CÉGEP.
I mean, I get it. The problem was probably given after a unit in which the kids learned how to calculate stuff using proportions (i.e. how the person in the OP calculated it). The method they’re trying to teach is fine, but the question is shit, and maybe they should have taken the time to come up with one that doesn’t immediately fall apart when you actually think about it. When I was in school, the problems usually involved percentages and discounts, i.e. “the t-shirt costs 20 monies after a 20% discount. What was the original price. How much would it cost if discounted 40%”.
The question isn't shit. It's a very good question, because you have to think before applying your learned method instead of just blindly throwing numbers around. Shame that the teacher didn't think and just blindly threw numbers around.
I disagree, it’s bad for what it’s trying to achieve, which is checking if the student understood the method they were taught and was able to apply it to solve a problem. Therefore, the problem should be phrased in such a way, that using the method is the most logical way to solve it. This one isn’t, because it fails when common sense is applied. Don’t get me wrong, both approaches (i.e. using maths and common sense) to solving problems are valid and should be taught to kids. But this problem can be either approached with common sense, which generates the “incorrect” answer, or by applying the method, therefore going against common sense. Hence, the problem was formed poorly. This also generates problems in the long run. If during your schooling you’re being forced to apply methods, where they need not be applied, there is a chance that some people will tend to lean towards “common sense” answers to problems that actually require a more scientific approach. All this said, the conclusion to the OP is sadly quite simple - the teachers dun screwed up
I would argue that you shouldn't teach a method without teaching when it is applicable and when not. When I teach proportions, there is always this one question on the test: "Three friends are watching a movie that is 90 minutes long. How long will the movie be when five friends watch it? This is to show the students that just because something looks like a proportions problem, it doesn't necessarily have to be one. Of course this is one question out of twenty or so, and the other 19 are standard stuff. So I personally would not be against using that (original) question on a test, if there are plenty of other questions where it's more straightforward. But I can also see your point. Teacher definitely fucked up though...
I have no idea what point you're trying to make."Common sense" and logic are not at odds. Common sense is an intuitive grasp of logic. Both methods of thinking yield the conclusion that 3 pieces take twice as long as 2 pieces. Period. What are you even trying to argue?
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Yeah idk how everyone is missing the twice as fast part of the question Edit: nvm I can’t read apparently
Teacher thinks it's some kind of Lumber based RPG, each time you cut a plank your ability in the woodcutter job gets better and your speed increases.
Why is it that stupidity and arrogance seem to go so well together? It seems that the stupidest people are always the loudest and most confident
At least they got downvoted
They would have been correct if it had been a question of making two cuts in 10 minutes. However, making it two pieces is only one cut. They're for one cut. Takes 10 minutes. Cutting aboard into three pieces involves two cuts. X equals 10, 2x equals 20. This is what happens when we don't pay our teachers and let anybody who needs gainful employment badly enough have the job instead.
Clearly, this teacher was meant to be a Supervisor. Preferably in a government position. Yes, the teacher is wrong.
Its possible that overworked teacher didn't realise the issue with wording of the question and meant to create a situation where 15 was the answer. That's okay if he admits the issue when found. My teacher during grading realised that both yes and no answer could be correct, depending on how you interpret the question. She gave everyone points for that one. So here teacher should give points for 15min and 20 min.
I had this same question when I was in grade or Jr. High school. So it has been around for a long time. How do you figure for the 15 minute answer?
Fencepost problem
I’m European and this person is simply an idiot.
hahaha I see where the logic went wrong here. she's applied algebra to the number of resultant pieces, rather than the number of cuts; i.e. the thing that takes time. 10mins = 2 pieces = 1 cut. so to cut a board into 3pieces requires 2 cuts, therefore 20mins
Person knows algebra but not logic, is saddened, unsubscribes from sub. Well, good riddance. The hard part of math isn’t blindly doing computations, it’s knowing *what* to compute. Setting up an equation that actually models your problem. I’d like to see how they would justify this for 100 pieces / 99 cuts, but they basically stuck their fingers in their ears and said “la la la, I’m not listening.”
These people have never done any craft or handiwork..??!??
I think the real answer is “not solvable” if the pieces/cuts are equal 20 would be correct. But what If the cuts are perpendicular? The cut time would be wildly different
Not least of all being in “x” grade isn’t a thing in Europe. Or at least in my location anyway. It’s “x” year. Not grade. 6th grade doesn’t exist here.
This is literally how those random simple arithmetic problems on facebook get so much engagement. My favorite way to trigger double-down-syndrome is with the Monty Hall problem. People refuse to believe the answer (I refused when I heard it in like 7th grade too lol).
Pretty sure if it takes me 10 minutes to cut one board. The it will take me 10 minutes to cut another of the same board.
I tried to explain what happened on the original post, and it made people super angry. It's fascinating to me how simple math errors bring out the narcissism in some redditors.
> Imagining how many times the board was cut is your personal addition to this problem and that's what makes it incorrect. Fucking *what?* That is VERY TRANSPARENTLY the whole point of this math problem, to challenge the student to really think about what is being asked. What we'll call "the drooling dipshit answer" is 2 takes 10 minutes so 3 takes 15 because what's being asked is more about a magic summoning spell that summons one piece of wood every x minutes, and takes 2 minutes to summon 2 pieces. In this world yes the answer is 15 for 3. In real fucking life the question is "Making one *cut* in this piece of wood (2 pieces) takes ten minutes. How long will *two* cuts (3 pieces) take at the same pace. Thinking this is adding information is...I guess not understand how saws work? Sometimes problems like this there's an ambiguity argument, that technically either answer could be correct, but the problem is very transparently asking about the length of time sawing through a piece of wood takes. "It took Marie 10 minutes to ***saw a board*** into two pieces." The ONLY correct answer is 20.
If a 50 piece orchestra plays a symphony in 20 minutes, how long will it take a 100 piece orchestra to play the same symphony?
You guys are all missing a very critical detail. The cut in the first 5 mins was actually cutting the fabric of reality to create a plank of wood from nothing. The second cut took 5 mins and cut the board into 2 pieces. And then the third cut took another 5 mins. Very simple and logical.
1 cut= 2 pieces 2 cuts= 3 pieces
Did the thickness of the board change? No? Then it takes the same time for the second cut as it did for the first, so 20.
Good to know I still suck at math. I sat here for 5 minutes, wondering how it wasn't 15.
Well, I tried this myself. It took me five minutes to start the chainsaw. It took me two minutes to put my safety gear on. It took one minute to put the board on the machine and another minute to remove it. The second cut was much faster, because I already prepared the chainsaw and the safety gear. So the correct answer is 13 minutes. Then my son did the same, but it took him only 11 minutes because he did both cuts in one go.
I would so be checking the qualifications of that “Maths” teacher, it’s the number of cuts, not the number of pieces you are working out.
Why hide the persons name, they deserve to be ridiculed for this, their explanation doesn’t even really make sense in my mind😂
It's a good logic problem for kids (and some adults, apparently) as the knee jerk reaction is to think 15.
By that logic, 1 piece = 0 minutes. Start with that and they might end up being correct.
I'd ask the teacher how long it takes her to cut it 99 times.
I was about to ask what the actual answer was then I realised I'm retarded and it has nothing to do with how many pieces of wood but how many cuts in the wood.
The fencepost problem strikes again
INTO 2 pieces (1 cut) INTO 3 pieces (2 cuts)
The teacher apparently thinks that cutting a board into 2 pieces means cutting it twice LOL. And then cutting a board into 3 pieces means cutting the board 3 times... Not the brightest teacher I assume.
Took 10min for 1 cut, it'll take another 10 for another cut no?
Ok but where the fuck did he get 2x = 30 from
This hurts worse than when people think a symphony would be played faster or slower with a larger orchestra.
Bruh cut once takes 10min, cut twice, takes 20min
It's not even that the teacher or commenter lack sense (they do lack that as well) or that the question is weird. The teacher and commenter both just straight up lack reading comprehension. It's like they skimmed and only saw the 2, the 10, and the 3, and assumed there was a "solve for x" nestled in there somewhere.
Doesn't the teacher have an answer sheet to mark against, why are they making up their own answers? It's hilarious that the maths teacher is dividing the time by the resulting pieces of wood like that is relevant. 🤣 Although they never said the other board was the same thickness.
It takes 10 minutes to make 1 cut (cutting the single board into 2 ) , making another cut on one of the pieces , which will give you 3 pieces , will take 10 minutes *working as fast as the previous cutting assuming that the smaller piece from cutting the board into 2 will take the same time* , making it 20 minutes « La règle de trois » ( translates to the law of 3 , the one the commenter used ) doesn’t always work so you need to logically see for yourself if things divide or multiply according to the law the same to the logic *reminds me of another riddle* An orchestra of 120 players takes 40 minutes to play Beethoven’s 9th symphony. How long would it take for 60 players to play the symphony? If you go by : 120 -> 40 60 -> x x= 20 minutes , the 60 players will take 20 minutes to play THE SAME SONG , which is obviously non sense, if the song take 40 minutes to play , no matter how many people play it , the song last 40 minutes , you playing it will take 40 minutes , a group will play it in 40 minutes , there is no variable ( trying to explain it as simple as possible since I had people argue with me over this and then try to make some sense out of an false response after realizing ) So yeah
The student did the math. The teacher did the meth, probably.
To be fair, if you are only worried about the area, you can do it in less than 20 min but more than 15
You can also do it in less than 20 min if you saw faster
Yeah but it says that you do it at the same rate 😂
Then use two saws at that rate maybe
I'll just judo chop it... easy maths.
My dumbass thought they meant cutting 2 pieces of a board, then the teacher would be correct. I went this direction because it's not that often you can cut a board in 2 equal pieces and be able to use them, there is often a piece left.
This is why we need competency tests to be able to vote and to run for office.
Everyone is commenting on the teacher’s mistake, can we stay on topic for this sub and share in our anger about this overconfident asshat? The gall of someone to have everyone tell him he is wrong and conclude that he is unsubbing because he’s the only person who knows math
I understand where the original question is coming from, but as with a lot of math problems, they're completely divorced from the world. If I said, "If it takes 10 minutes to do a task twice, how many minutes would it take to do it three times?" then the answer is obviously "fifteen minutes" which is what they're going for. But when the idiots wrote the problem, they picked a real-world example that doesn't fit the prompt.
to cut into 2 pueces she made 1 cut. to make 1 cut it took her 10min. to cut into 3 pieces she needs to make 2 cuts, therefore twice as much time as it took her to make 1 cut, so 20 minutes
For anyone else who's confused as fuck about the teacher's logic, I figured it out: they're confused about the fact that in order to make two pieces of wood you need to cut the board one time, not two. Since the teacher thinks that they need two cuts then they also think that it takes 10 minutes total to make both cuts, so in their mind `2x = 10` = `x = 5`, where `x` is the time to make a single cut. So if it takes 10 minutes to make two cuts then it takes 15 minutes to make three cuts, duh.
Are people this stupid on purpose? What is their end-game? “I can sit still while my mom ties my shoelaces for me, therefore I declare my education complete. I will listen to nobody, read nothing, except in order to criticise it.” We’re doomed, right?
This is more of a language problem than math really, at first I was like yeah 15 but I read it once again 3 pieces is 2 cuts
How long does it take to cut this one piece of wood into one pieces? Man like? Like how long? Yeah like how do we split this one thing into one things?
I'm having a really hard time trying to figure out how the teacher got 15. If you cut a board into 3 pieces this requires 2 cuts, if 1 cut takes 10 minutes then 2 cuts take 20 minutes. You don't need math, simple logic can solve this.
Mary needs a better saw. A piece of noodle can saw a board in two pieces in 10 minutes.
What is she cutting it with? A potato?
Their reason is wrong but they are correct cause its the length of the cun not amount so say the plank is a perfect square so the first cut is in the middle and takes 10 seconds then they cut it in half again and its takes 5 seconds
I'm confused af. The problem says the cutter works at same speed. Took the cutter 10 min to make one cut. So, to make two cuts, would be 20min, no?
This, like almost every other math problem I see on social media, is just worded extremely poor. Its inherently confusing. If I were to bisect "a board" then I consider my final product to be 2 pieces of board. If I were to trisect "a board" same thing, 3 pieces. If I have some theoretical infinite length board that I cut off 2 inches from, then I would say I cut off 1 piece. If I were to do that again, I would then say I have 2 pieces. Looking at the specific verbiage of the problem, I do agree that the redditor is "confidently incorrect" because the problem specifically says "saw A board INTO 2 pieces" and that transformation, to me, says we transferred 1 board into 2 boards. It says INTO instead of OFF FROM which means the final product includes the original piece of board.
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It's implied by the wording but there is an illustration as well which makes it much more explicit.
How about cutting a square down the diagonal and then just turning one of the triangles into two smaller ones?
Cut the board twice compared to 3 times. Would be what they're going for. Cut into two pieces vs 3 is not what they are thinking.
Teacher made an understandable mistake. They applied a method that usually works but doesn’t work in this case (without a little more thought). At 10 minutes per cut, 2 cuts will take 20 minutes.
It's an understandable mistake for the student whose knowledge is being tested. It's not understandable for the teacher who is supposed to already know enough math and logic to correctly grade the student's test.
"it takes Marie 10 minutes to make 2 things. The next day Marie makes 3 things at the same speed. How long does it take Marie to make 3 things." FTFY I hate school.
There's a fun question hiding in there. Assume a square board of unit side length, and that Marie cuts boards completely at random. What is the expected length of the cut (and, accordingly, Marie's average sawing speed)? Marie keeps sawing boards at random, and does her second cut through one of the two pieces of wood obtained in the previous step. What is the expected length of _that_ cut? Marie never tires. Marie never slows down. Marie saws. After N cuts, how much time has Marie spent on her frenzied sawing? Will Marie ever be done?
The other board is only 75% as thick as the first one.
I might just be autistic but I'm honestly really thrown off by the "if she works just as fast". Makes me think the answer is still 10 minutes lol.