5 . Customers arrive at the drive - through lane of a fast food restaurant at a rate of one every 3 minutes . Use the Poisson probability distribution to answer the following questions : ( 8 points ) a . What is the expected number of customers in one hour ? b . What is the probability that exactly two customers arriving at the drive - through lane in a nine - minutes interval ?! C . What is the probability that less than two customers arrive at the drive - through lane a nine - minutes interval ?" d . What is the probability that two or more customers arrive at the drive - through lane a nine - minutes interval