21. Using the Empirical Rule An experiment is designed to test the effectiveness of the MicroSort method of gender selection, and 100 couples try to have baby girls using the MicroSort method. Assume that boys and girls are equally likely and also assume that the method of gender selection has no effect.

a. Using the methods of this section, what are the minimum and maximum usual numbers of girls in groups of 100 randomly selected babies?

b. The empirical rule (see Section 3-3) applies to distributions that are bell-shaped. Is the binomial probability distribution for this experiment (approximately) bellshaped?

How do you know?

c. Assuming that the distribution is bell-shaped, how likely is it that the number of girls will fall between 40 and 60 (according to the empirical rule)?