A man has two children. At least one of them is a boy. What is the probability that both children are boys?
The probability that both children are boys is 1/3.

Here's the reasoning:

1. Since at least one child is a boy, there are three possible scenarios for the genders of the two children: Boy-Boy, Boy-Girl, or Girl-Boy.
2. We want to know the probability of the scenario where both children are boys (Boy-Boy).
3. Out of the three possible scenarios mentioned above, only one of them meets our condition (Boy-Boy).
4. Therefore, the probability that both children are boys is 1 out of the 3 possible scenarios, which equals 1/3 or approximately 33.33%.