Question

Most people think babies are equally likely to come as either a boy or a girl. this is not true. actually, about 51.3% of all babies are boys. if a family has two children (not twins), what is the chance they have one boy and one girl? round your answer to two decimal places.

Answer 1

49.97% For this problem, let's consider the probability of each of the four possibilities for having two children, being BB, BG, GB, and GG. Then sum the probabilities for both the BG and GB events. So BB = 51.3% * 51.3% = 26.3169% BG = 51.3% * 48.7% = 24.9831% GB = 48.7% * 51.3% = 24.9831% GG = 48.7% * 48.7% = 23.7169% If you check, you'll notice that the sum of all the probabilities add up to 100% like it should. And the sum of BG + GB is 24.9831% + 24.9831% = 49.9662% which when rounded to 2 decimal places is 49.97%