How Many Sons? (Solution)

Then answer is \(\frac{1}{3}\).

Jane has two children. From this, we start with four, equally likely, possibilities: BB BG GB GG.

Jane has at least one son. So we now know that only three of the four possibilites satifsy this condition: BB, BG, GB.

What’s the chance that she has two sons? Jane only has two boys in one of the three (equally likely) possibilities, so \(\frac{1}{3}\).