## 1996-07 Solution

There are two possible ways of having two children (first second): MM
MF FM FF. If he says one is a boy, that eliminates FF, so there are only
three possible combinations remaining: MM MF FM. Of these, two have girls
as the other child, so the chance is 2/3. (The answer to the supplementary
question is 1/2, as expected, since the only remaining combinations after
the first sentence are MM and MF, and the other one is a girl in 1/2 of
them.)

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