Scenario B.3 Customers Arrive at a Bank for Service,forming a Single Line

Multiple Choice

Scenario B.3
Customers arrive at a bank for service,forming a single line to wait for the first available of three tellers.They arrive at the rate of 45 per hour and are served by the first available teller,who can service customers at a rate of 20 per hour,following a Poisson distribution.Customer arrival times are governed by the exponential distribution.
-Use the information in Scenario B.3.What is the average time a customer spends in the system?

A) fewer than or equal to 5.0 minutes
B) greater than 5.0 minutes but fewer than or equal to 6.0 minutes
C) greater than 6.0 minutes but fewer than or equal to 7.0 minutes
D) greater than 7.0 minutes