16 December 2012
Probability of a son
Strictly speaking, it is not puzzle time since I am flying out of Atlanta not to Atlanta. But what the hell, it is holiday season… so, here goes..
I was addressing a large audience this morning and asked those who have two kids to raise their hands. Then I asked – of all the people who have their hands raised – to keep their hands raised if one of their child is a son born on a Sunday. They rest can put their hands down. Now I picked any one from the ones left with their hands raised. What is the probability that their other child is a son?
(assume equal probability for having a son or a daughter or which day of the week a child is born).