Question 2 (25 POINTS): Customers arrive at a one-window drive-in bank according to a Poisson distribution, with a mean of 10 per hour. The service time per customer is exponential, with a mean of 4 minutes. There are three spaces in front of the window, including the car being served. Other arriving cars line up outside this 3-car space. a) d) What is the probability that an arriving car can enter one of the 3-car spaces? How long is an arriving customer expected to wait before starting service? What is the expected number of customers in system? How many car spaces should be provided in front of the window (including the car being served) so that an arriving car can find a space there at least 90% of the time?