What a Family Planning Strategy Can Teach Us About Investing

Imagine a country where all couples have their hearts set on having a baby girl, and so each family keeps having children until they have one girl, and then they stop. This is a thought experiment, so let’s assume that women in this hypothetical country can give birth as many times as needed until they have a girl, and that the probability of having a girl is 50% for each birth, irrespective of how many boys the family has had so far.

The expected number of girls in this country is ______ the expected number of boys?