Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

Exercise 43

Private Investigation: Locating People Old Friends Information Service is a California company that is in the business of finding addresses of long-lost friends. Old Friends claims to have a 70% success rate (Source: The Wall Street Journal ). Suppose that you have the names of six friends for whom you have no addresses and decide to use Old Friends to track them.
(a) Make a histogram showing the probability of r = 0 to 6 friends for whom an address will be found.
(b) Find the mean and standard deviation of this probability distribution. What is the expected number of friends for whom addresses will be found