Weary Travelers Arrive at Will Rogers International Airport, Pick Up

Multiple Choice

Weary travelers arrive at Will Rogers International Airport, pick up their luggage, stumble to their cars, and proceed to the parking lot attendant to pay for their parking. Traveler interarrival times are exponentially distributed, as are the service times of the attendant. On average, travelers arrive every 25 seconds. The attendant can process three travelers per minute.
-Use the information in Scenario C.2.How many minutes per hour is the attendant not serving customers?

A) Fewer than or equal to 13
B) Greater than 13 but fewer than or equal to 17
C) Greater than 17 but fewer than or equal to 21
D) Greater than 21