EDGE Math 8

Example 2

If a family with three children is selected at random, what is the probability of choosing a family with at least one boy?

Solution

The sample space for a family with three children is given by S = {BBB, BBG, BGB, BGG, GBB, GBG, GGB, GGG}. Hence, $N = 8.$

The event of choosing a family with at least one boy is given by A = {BBB, BBG, BGB, BGG, GBB, GBG, GGB}. Therefore, $n = 7.$

The probability of choosing a family with at least one boy is

P (A) = \frac{n}{N} = \frac{7}{8} .