6. A local bank has two drive-thru teller windows with an essentially unlimited queue length. They estimate that the arrival rate during their most busy time will average about 40 cars per hour. They also estimate they can serve an average of 50 cars per hour. Management wants to make sure that the system is operating efficiently. a) What is the probability that there will be no cars in the system? b) On average, how many cars are in the system? C) How long would a car be waiting (in seconds) in the driveway, on average