Use of laughing gas. According to the American Dental Association, 60% of all dentists use nitrous oxide (“laughing gas”) in their practice. If x equals the number of dentists LO9 in a random sample of five dentists who use laughing gas in practice, then the probability distribution of x is x 0 1 2 3 4 5 p1x2 .0102 .0768 .2304 .3456 .2592 .0778

a. Find the probability that the number of dentists using laughing gas in the sample of five is less than unity.

b. Find E1x2 and interpret the result.

c. Show that the distribution of x is binomial with n = 5 and p = .6.