Question $-4$: Problem Solving:

In a service location,

$=40$

$=9$

Currently: There are $4$ servers each able to process $9$ customers$/$hour$.$ customers arrive at a rate of $40$ customers per hour. Interarrival times and service times are exponentially distributed.

Option #$1$: Hire $2$ more servers.

A$.$ For all the two situations $($current$,$ option #$1),$ what is the notation for each system?

B$.$ For both situations, is the system stable? why?

C$.$ On average, how many customers are waiting in line? $($Select the proper unit$)($for each sy if applicable$)$

D$.$ On average, how long does a customer spend in the waiting line in minutes? $($for each s$)$ applicable$)$

E$.$ What is the probability that $7$ or less people are in the system? $($for each system if ap$]$