Using the same sample space and assumption from Exercise 35, find the probability that when a couple has four children, all four are of the same gender.

Exercise 35

Use this sample space listing the eight simple events that are possible when a couple has three children (as in Example 2 on page 155): {bbb, bbg, bgb, bgg, gbb, gbg, ggb, ggg}. Assume that boys and girls are equally likely, so that the eight simple events are equally likely. Find the probability that when a couple has three children, there is exactly one girl.