You are in your friend's home.You are asked by your friend,
a mathematician to enter a totally dark room and to pick up a pair of socks from a certain drawer.
You are told that there are some socks in that drawer, and that each can be either black or white.
You are told as well that the probability of picking at random two black socks is 1/2.
What is the probability of taking out a pair of white socks from the drawer?
(In reply to
the big drawer by Ady TZIDON)
I forgot there were originally 4 socks. Yes, that was too simple. For a simple (but not too simple) problem you could have made it "fewer than 10 socks." Fortunately you removed the sock number completely.
I didn't foresee multiple solutions when this was removed. I didn't think it would up the D. I suppose that is the danger of editing problems 'by committee' but here we got a bonus: a quite interesting result.

Posted by Jer
on 20150930 08:43:31 