2 ms·
>If the man is randomly chosen from the set of all families the answer is 1/2. By assumption, the man has a son born on Tuesday, so this is hardly relevant. I
by anorwell 15y ago
>If the man is randomly chosen from the set of all families the answer is 1/2.
By assumption, the man has a son born on Tuesday, so this is hardly relevant.
If A is a subset of B, then choosing x uniformly at random from A given that x is in B is the same as choosing uniformly at random from B.
- monorailkitty 15y agoI agree but set B is not a uniformly chosen subset of A in this case. That is the core of the trick. The rule for choosing B is intuitively uniform but actually slightly favours families with a girl and a boy over those with two boys.