Multiple Server, Exponential Service Time: Problem$-6$

An average of $18$ customers arrive at a service center each hour.

There are two servers on duty, and each server can process $12$

customers per hour.

$1)$ What is the system utilization?

$2)$ What is the average number of customers in the system $($waiting

plus being served$)?$

$3)$ What is the average time customers wait in line for service?