Question
A family has two children. What is the probability that both the children are boys given that at least one of them is a boy?
Solution
Let b stand for boy and g for girl.
∴ S = {(b, b), (g, b), (b, g), (g, g)}
Let E and F denote the following events:
E : ‘both the children are boys’
F : ‘at least one of the child is a boy’
∴ E = {(b, b)} and F = {(b, b), (g, b), (b, g)}
Now, 
