Neve Commercial Bank is the only bank in the town of York, Pennsylvania. On a typical Friday, an average of 10 customers per hour arrive at the bank to transact business. There is currently one teller at the bank, and the average time required to transact business is 4 minutes. It is assumed that service times may be described by the exponential distribution. If a single teller is used, find:

a. The average time in the line.
b. The average number in the line.
c. The average time in the system.
d. The average number in the system.
e. The probability that the bank is empty.