Q. willow brook national bank operates a drive-up teller window that allows customers to complete bank transactions without getting out of their cars. On weekly mornings, arrival to drive-up teller window occurs at random, with an arrival rate of 24 customers per hour or 0.4 customers per minute.

A. What is mean or expected number of customers that will arrive in a five-minute period?

B. Assume that Poisson probability distribution can be used to describe arrival process. Use arrival rate in part (a) also computes probabilities that exactly 0, 1, 2 also 3 customers will arrive during a five-minute period.

c. Delays are expected if more than three customers arrive during any five-minute period. What is probability that delays will occur?