There are $4$ servers in the checkout area. The average interarrival time of customers is $2$ minutes $($one customer arrives every $2$ min on average$).$ The average service time is $3\mathrm{.}0$ minutes$/$customer by an individual server. What is the overall server utilization?

Question $9$ options:

$0\mathrm{.}625$

$0\mathrm{.}554$

$0\mathrm{.}375$

$0\mathrm{.}400$