Alice and Bill are planning to have three children. (Assume that it is equally likely for a boy or a girl to be born.)

Question

What is the probability that not all three will be of the same gender?

Answer 1

P(not all same)
= 1 - P(all same)
= 1 - (P(all boys) + P(all girls))
= 1 - (1/8 + 1/8)
= 3/4