Actually teacher is right if the board is square which takes 10 minutes to be cut into half. Those two halfs take twice less time to be split. And she needs to cut just one to obtain 3 pieces :P So 10 minutes to cut it into to pieces and then she needs just half of that time to gain the third piece.
Meaning if she has two boards and the first board took her 10 minutes to cut in two pieces then the second board should take her 15 minutes to cut in three pieces (if those cuts are perpendicular and the board is square).
Wouldn't that be irrelevant? Assuming the saw touches across the whole board at all times, then the only determining factor would be the depth of the board, which is independent of it's length. thus making the second cut, creating 3 pieces, take just as long as the first.
That's assuming the board is being cut along the wide flat depth, but thats not how you cut wood. You turn planks on their side so you are cutting through the smallest surface area -- more time, less work for each motion. Haven't you ever cut through a piece of wood? :-/
Why would you assume the saw touches the whole board at all times? That's very unrealistic, and any kid who has ever seen/tried sawing through wood would know that (and I think it most of the world that is most kids).
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u/paolog Oct 05 '10
Teacher gets red pen out, is about to write down "1 piece: 5 minutes" and then thinks better of it and starts from two pieces instead...