Source:

In a country in which people only want boys, every family continues to have children until they have a boy. If they have a girl, they have another child. If they have a boy, they stop. What is the proportion of boys to girls in the country?

Answer next week.

EDIT 4/26: Answer.

This one is funny. I like it because you can answer it without any math whatsoever: the event is random, and you can’t control random.

It applies to _any_ way to try to skew the distribution.