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Probability 5.0/10

Two Children

A family has two children. You learn that at least one of them is a boy. What is the probability that both are boys? (Assume boys and girls are equally likely and genders are independent.) Express as a fraction.

Related problems & prerequisites

Worth solving first

Source: The two-children problem, posed by Martin Gardner in Scientific American (1959). Statement written for AxiomIQ.