Quote:
Originally Posted by echarcha
Thank you for staying on topic and giving the right answer. Yes, it takes 10 minutes to cut a board into two pieces. So no matter what, it will always take 10 minutes to cut the board. So the right answer is 20 minutes.

The right answer is
15 minutes.
The implicit assumption being that the board is of a particular shape and will be cut in a certain way.
Take a piece of square board. Cut along lengthwise (or width wise, it does not matter in the first cut). The time it takes is 10 minutes (as stated).
Now, take one of the two pieces so generated, and cut it along its shortest dimension. Because the shortest dimension is one half the other dimension, the time taken is one half as well. Thus the time required is 5 minutes.
The total time is 10 + 5 = 15 minutes. The pieces generated are 3, one big and two small pieces.
Obviously, I think otherwise