Customers Arrive at a Suburban Ticket Outlet at the Rate

Multiple Choice

Customers arrive at a suburban ticket outlet at the rate of 14 per hour on Monday mornings (exponential interarrival times) . Selling the tickets and providing general information takes an average of 3 minutes per customer, and varies exponentially. There is 1 ticket agent on duty on Mondays.
What is the system utilization?

A) 0.6
B) 0.7
C) 0.8
D) 0.9
E) 1