today's fun with probability
Nov. 20th, 2002 07:33 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
eub1) You meet a man at the bowling alley [this is how it was posed, honest]. He has two children, bowling on lane 17. You see one girl there; the other child doesn't happen to be visible.
2) Man, bowling, two children. You ask if he has any daughters. He says yes.
In each case (any difference?), what's the probability that he has two daughters?
Assume male and female are mutually exclusive and 50-50 and independent between children. Make any further assumptions you need.
[edit: spoilers in comments, natch]
2) Man, bowling, two children. You ask if he has any daughters. He says yes.
In each case (any difference?), what's the probability that he has two daughters?
Assume male and female are mutually exclusive and 50-50 and independent between children. Make any further assumptions you need.
[edit: spoilers in comments, natch]
no subject
Date: 2002-11-21 07:51 am (UTC)assuming (in the first case) that he is equally likely to bring boys or girls with him to bowl,
the problems are equal, and it's a 50-50 chance. Seeing the girl, or being told he has a daughter, eliminates one child from consideration, so this reduces to the probability of an unknown child being female, which you have said is 50-50.
Now I'll go read the spoiler comments and see how far off I am. :-)