Math problem: Who is correct, The Teacher or The Student?

[LumbergTech]

this thread must be immortalized.....hilarious how such a simple problem can confuse such as large group

 

[HamburgerBoy]

If you cut along the 6" side you will end up with two 6x6" squares, not two 3x12 boards.

My wording may be wrong, but the point is that you're cutting into the dimension that corresponds to the shorter side, in which case my argument is still valid.

To get 20 min total he cut the other 6x12 board not the 3x12 board as you have done.

Why? That's arbitrary, and if silly assumptions *must* be made, it's not too silly to assume that the student will want to maximize the rate of cutting.

What, lol. Are you serious, lol.

I have one 12 x 12 board

First cut produces two 6 x 12 boards.

Take one of those pieces and now my second cut split the board in two. But I will cut the length of the smaller plane, which is 6 inches

At the end I have one 6 x 12 and two 6 x 6.

If I slice the other board I will have four 6 x 6 pieces.

LOL, where you learn how cut, hehehehehehe.

But again this is all speculation because no dimensions were given. We assume the board is like in the picture, but obviously that was not the case. And if you apply this same formula to other case that don't involve board cutting, with a board like in the picture, then teacher is correct.

A lot assumptions.

The question didn't say anything about the boards having to be of equal size. One could come up with many possible ways to get the different values provided by the teacher, but it is obvious where the teacher went wrong.

 

[silverpig]

My wording may be wrong, but the point is that you're cutting into the dimension that corresponds to the shorter side, in which case my argument is still valid.

No, if you cut along the shorter side (so the time is shorter) you'll end up with two 6x6 boards and not two 3x12 boards.

To get two 3x12 boards you have to cut the 6x12 board along the longer dimension, thus still doing a 10 minute 12" cut.

 

[HamburgerBoy]

No, if you cut along the shorter side (so the time is shorter) you'll end up with two 6x6 boards and not two 3x12 boards.

To get two 3x12 boards you have to cut the 6x12 board along the longer dimension, thus still doing a 10 minute 12" cut.

?

 

[arkcom]

?

The third cut is still 6 inches. The fourth will be 3.

 

[SKORPI0]

Interesting thread from Oct 2010.

http://boards.ign.com/teh_vestibule/b5296/196505368/p1

 

[HamburgerBoy]

The third cut is still 6 inches. The fourth will be 3.

Oh fuck, you're right. I just went back to my highly detailed MSPaint diagram and drew red lines indicating where the cuts were and now I get it. My apologies and stupidity for that.

 

[TuxDave]

You are as bad as the teacher. If your first cut gives you a 1m and 19m piece, and the next cut gives you 2x 1m pieces and an 18m piece, why does the second cut take half the time???

Reread the question as I stated it:

"say you have a 20 meter long stick and you're trying to make 1 meter pieces"

To make two 1 meter pieces, it takes 2 cuts totalling 10 minutes of work (5 minutes a cut). Therefore to get the 3rd 1 meter piece, you need a 3rd cut and therefore total 15 minutes. Make sense?

(ignore the fact that if you could cut two pieces of wood at the same time you could techincally reduce it to two total cuts)

 

[classy]

Reread the question as I stated it:

"say you have a 20 meter long stick and you're trying to make 1 meter pieces"

To make two 1 meter pieces, it takes 2 cuts totalling 10 minutes of work (5 minutes a cut). Therefore to get the 3rd 1 meter piece, you need a 3rd cut and therefore total 15 minutes. Make sense?

(ignore the fact that if you could cut two pieces of wood at the same time you could techincally reduce it to two total cuts)

You know you are correct, wow. The question never states you are cutting a single piece of board into 3 or 4 pieces. Damn dude, kudos to you. :thumbsup:


Edit**** I don't know though, the question gives you the impression she cut a single board into two pieces. But then it says what if she took another board................................

We need the damn teacher to explain the wording on this question.

 

[HamburgerBoy]

You know you are correct, wow. The question never states you are cutting a single piece of board into 3 or 4 pieces. Damn dude, kudos to you. :thumbsup:

Edit**** I don't know though, the question gives you the impression she cut a single board into two pieces. But then it says what if she took another board................................

We need the damn teacher to explain the wording on this question.

The question explicitly asks how long it would take to cut another board (i.e. a single one) (not that it would matter if it was a piece of the previous board or a brand new one assuming one doesn't change the direction of cutting) into three pieces.

 

[TuxDave]

You know you are correct, wow. The question never states you are cutting a single piece of board into 3 or 4 pieces. Damn dude, kudos to you. :thumbsup:


Edit**** I don't know though, the question gives you the impression she cut a single board into two pieces. But then it says what if she took another board................................

We need the damn teacher to explain the wording on this question.

Meh, I wouldn't worry about it too much. The question wording is terrible and so if you really wanted to, 15 or 20 could be a reasonable answer. Let's say she's cutting a board into pieces shaped as circles. Then to make three pieces you need 15 minutes since making two circles took you 10.

 

[PlasmaBomb]

To get 20 min total he cut the other 6x12 board not the 3x12 board as you have done.

This question is pretty straightforward and some of your are making it more complicated than it needs to be. If it took Marie 10 minutes to make 2 pieces then that means she can make 1 piece every 5 minutes. If three pieces are needed then the answer is 5 minutes per piece x 3 pieces = 15 minutes.

***BUZZZZZZZZ*** Wrong answer

Marie started out with one piece of wood. It took her 10 minutes to cut the wood, which gave her two pieces.

Assuming that she cuts at the same rate how long would it take her to cut another piece of wood into three pieces?

 

[PlasmaBomb]

We assume the board is like in the picture, but obviously that was not the case. And if you apply this same formula to other case that don't involve board cutting, with a board like in the picture, then teacher is correct.

A lot assumptions.

No the teacher is not correct if the board is a plank as pictured...

 

[PlasmaBomb]

Meh, I wouldn't worry about it too much. The question wording is terrible and so if you really wanted to, 15 or 20 could be a reasonable answer. Let's say she's cutting a board into pieces shaped as circles. Then to make three pieces you need 15 minutes since making two circles took you 10.

In the example she started out with one piece of wood. If she was creating circles it would take 20 minutes to make two circles as she starts out with none...

 

[TuxDave]

In the example she started out with one piece of wood. If she was creating circles it would take 20 minutes to make two circles as she starts out with none...

10 minutes to make 2 pieces as stated in the original question. We all assume 2 pieces mean two chunks of whatever. (mainly 1 cut to turn chunk of wood into two chunks of wood). I'm saying if you can find a way such that two "pieces" = two cuts, aka turning a plank into circular pieces, then 15 is fine. 10 minutes to make two circular pieces (two cuts). A third cut to make the 3rd circular piece is an extra 5 minutes.

Please don't try to get me to argue with you on such a stupid thread.

 

[sandorski]

I understand what the teacher wanted, but the teacher worded it in a way where the student was right.

I suspect this is the problem. The Teacher probably meant some board of n length and each cut was only a small part of n. Thus 2 Cuts were required to achieve the desired 2 pieces in the first part of the problem.

 

[Jeff7]

So how long would it take to cut the board into 1 piece?

:hmm:

 

[Chaotic42]

I don't get why people are still having issues with this. You aren't allowed to add any extra information to the problem.

"It took Marie 10 minutes to saw a board into 2 pieces. If she works just as fast, how long will it take her to saw another board into 3 pieces?"

The answer is 20. Her work speed is 1 cut per 10 minutes. Thus 2 cuts will take her 20 minutes. If we followed the teacher's math, it would take her 5 minutes to end up with 1 piece of wood.

Think about that for a second.

It would take her 5 minutes to make 0 cuts. That makes no sense. 0x=5 has no valid solutions. That's it. No crazy wood sizes, no deus ex machina wood cutting lightning bolts, nothing. 0x=5 has no valid solutions for x.

 

[sandorski]

I don't get why people are still having issues with this. You aren't allowed to add any extra information to the problem.

"It took Marie 10 minutes to saw a board into 2 pieces. If she works just as fast, how long will it take her to saw another board into 3 pieces?"

The answer is 20. Her work speed is 1 cut per 10 minutes. Thus 2 cuts will take her 20 minutes. If we followed the teacher's math, it would take her 5 minutes to end up with 1 piece of wood.

Think about that for a second.

It would take her 5 minutes to make 0 cuts. That makes no sense. 0x=5 has no valid solutions. That's it. No crazy wood sizes, no deus ex machina wood cutting lightning bolts, nothing. 0x=5 has no valid solutions for x.

One possible way the Teacher could be correct is if there was a pre-condition to this section of mathematical problems. Defining what length each cut were to produce and some n length of the original Board much larger than the desired lengths, even after many more cuts than being asked.

This question in isolation was certainly answered correctly by the student.

 

[SKORPI0]

This question in isolation was certainly answered correctly by the student.

That's the way to treat it, based on data that was given. Do not over analyze on something that never existed or making new assumptions. Plain and simple.

 

[silverpig]

Uh...

12x12 cutting for 10 minutes produces two 6x12 boards.

Cut one 6x12 board along the 6 and you now have one 6x12 board and two 3x12 boards (three boards total). Half the distance means half the time means an additional 5 minutes.

Cut the 3x12 board along the 3. This results in two 1.5x12 boards along with a 6x12 board and a 3x12 board (four boards total). Cutting it takes half as long as a 6x12 board, meaning an additional 2.5 minutes.

Add them up: 10 + 5 + 2.5 = 17.5. Unless I'm not understanding the dimensions (I mean, I do find it highly odd that everyone is talking about boards and rods as if they are two-dimensional), you're wrong.

?

The picture does not reflect what you described. As I said, you will end up with two 6x6 boards as your picture shows. Your post says you end up with two 3x12 boards.

 

[sandorski]

That's the way to treat it, based on data that was given. Do not over analyze on something that never existed or making new assumptions. Plain and simple.

Pretty much, but there is always the possibility that the OP or whomever first brought this situation to the Internet was being either deceitful or simply overlooked another factor. With the intent of gaining moral support from the Internet. If that were true, we'd all have been trolled by some naive spoiled little brat throwing a tantrum.

 

[jcurry5]

Taking the question at hand, it will take 20 minutes. One cut takes 10 minutes which gives you two pieces. To get a third piece, you have to make a second cut on the new board which will take 20 minutes.

It seems obvious the teacher wanted the student to do 10 over 2 times x over 3 to get 30/2 which gives you 15.

With an explanation, the student shouldn't get it wrong for answering the question correctly.

 

[yhelothar]

Brilliantly done sir. 😀

That would very much qualify to be a valid scenario under classy's line of reasoning.

 

[classy]

Brilliantly done sir. 😀

That would very much qualify to be a valid scenario under classy's line of reasoning.

Oh grow up and stop acting like a little baby. I am one of many others who can see how the correct answer could be 15. I at least have the sense to give the teacher rather than the student the benefit of the doubt.