Campus Security provides Safety Assistants $($SA$)$ to help escort students who are walking back to their dorm in the evening $(7$ PM $$ midnight$).$ The time it takes a SA to walk a student home is normally distributed with a mean of $18$ min and standard deviation of $9$ min. There are $10$ SAs and, currently, each student is assigned to a specific SA$.$ Whenever a student places a request, the request is routed to their assigned SA$.$ The interarrival time of requests for each SA is $25$ min and is exponentially distributed