OK, @Krasimir_Georgiev was righ heret. The correct answer is 20 minutes. @Krasimir_Georgiev wins the big prize - 5 beers. He can collect them at the PointDebate office near Herbs' pub.
Some people are deluded into believing that 15 minutes is the correct answer because they mistakenly take into account the number of the board pieces in the end, not the number of sawings.
Even math teachers fall in the trap:
http://i.imgur.com/65APr.jpg

@Valentin_Ivanov, it's a thick wooden board and a blunt saw. Don't avoid the question, I know you are good at maths :)

Why does it take her 10 fucking minutes to cut a board into two? :)

@Steliyan_Petkov_Georgiev, the third-grade thing complicates things (because it looks like a first-grade one :)).

20

Come on? Anyone? It's not that hard, it's a third-grade mathematical problem. Do not be scared that you are going to embarrass yourself.

The pieces dimensions and shape are not part of the definitions of this problem. We can say they are the same for both sawings.

Are we supposed to answer this without knowing the board's dimensions or how she wants the pieces cut?