A traditional call center has a simple mission: Agents have to answer customer calls fast and end them as quickly as possible to move on to the next call. The quality of service rendered by the call center was evaluated by recording the number of times a customer called the center back within a week of his or her initial call to the center.

a. What is the probability that a customer will recall the center more than three times?
b. What is the probability that a customer will recall the center at least two times but less than five times?
c. Suppose a call center must notify a supervisor if a customer recalls the center more than four times within a week of his or her initial call. What proportion of customers who contact the call center will require a supervisor to be contacted?

y number of recalls 0 P(y) 151 232 354 16 067 021 014