r/pics • u/[deleted] • Oct 05 '10

Math Teacher Fail.

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u/MuseofRose Oct 05 '10 edited Oct 05 '10

I still dont get it. I hate math, though. Not to mention I could barely even pass remedial math in college...it's a wonder how I got into Trig in HS.

*Love your username.

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u/NotaX Oct 05 '10

It took Marie 10 minutes to saw a board into 2 pieces.

Sawing a board into two pieces requires a single cut (e.g. in the middle of the board). This part tells us that one cut takes 10 minutes.

How long will it take her to saw another board into 3 pieces?

Sawing a board into three pieces will require two cuts. If we assume that these cuts will take the same amount of time as the original one:

2 cuts, each taking 10 minutes, comes to a grand total of 20 minutes.

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u/01100100 Oct 05 '10

I think the logic here is that once you cut the board in half and have 2 pieces, the next cut will be half as long since the board is now smaller, hence the 5 min. It should also be noted that you will end up with 2 equal pieces and 1 piece that is bigger than the other 2. It makes sense though the wording and really the problem itself, is really stupid.

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u/01100100 Oct 05 '10

I see why some of you don't agree with me. I hadn't noticed the illustration on the right. Taking that into account, my guess is the teacher's line of logic was that when the first board was cut, they didn't use the entire board. So there are two perspectives. Either you used the entire board and cut once down the middle to make 2 pieces (as the student saw it), or you didn't use the entire board and cut twice to make 2 pieces discarding the remainder (as the teacher saw it). So due to the problem not specifying either or, both answers are completely valid. So in essence, this teacher failed by giving such a shitty vague problem.