15. What is the probability of observing a value of z greater than 1.43 or less than 21.43? What might you conclude about the average number of Facebook friends? It is reported1 that the average or mean number of Facebook friends is 155. Suppose that when 50 randomly chosen Facebook users are polled regarding the number of their friends, the average number of their friends was reported to be x 5149 with a standard deviation of s529.7.