8.

Assume that male and female births are equally likely and that the birth of any child does not affect the probability of the gender of any other children. Suppose that 650 couples each have a baby; find the mean and standard deviation for the number of girls in the 650 babies.

9.

A sales firm receives an average of four calls per hour on its toll-free number. For any given hour, find the probability that it will receive exactly five calls. Use the Poisson distribution.

8. Assume that male and female births are equally likely and that the birth of any child does not affect the probability of the gender of any other children. Suppose that 650 couples each have a baby; find the mean and standard deviation for the number of girls in the 650 babies. (3 p) 9.A sales firm receives an average of four calls per hour on its toll-free number. For any given hour, find the probability that it will receive exactly five calls. Use the Poisson distribution. (2p)