Earlier quoted context omitted.
> But since the boy could be either the younger or the older child, the analysis is more subtle. Devlin started by listing the children’s sexes in the order of their birth Personally, when I read that I could spot the error. For lazy people (tl;dr types) ... order doesn't matter as you're not given any info about that order. So given 2 children, there are only 3 possibilities ... boy, boy girl, girl boy, girl So if y…
Actually, I'm going to stop now: http://xkcd.com/386/ It's pretty clear I won't convince you. Let me leave you with these questions: If I toss two coins until at least one shows a Head, what's the probability that both are Heads? If I roll two dice until at least one shows a 6, what's the probability that both are 6's? If I spin two roulette wheels until at least one shows a Red-23, what's the probability that both a…
You're only selecting two child families.
Flip one million coins. Select two at random. If one of them is heads, what is the probability that the second coin is heads?