At the local post office, customers join a single line where they are routed to the first available of $3$ postal service workers for help with their transaction, e$.$g$.$ purchasing postage, weighing the package, answering questions. The time it takes the postal service worker to complete the transaction is $4\mathrm{.}7$ minutes on average with a standard deviation of $5\mathrm{.}6$ minutes. During the busy holiday rush, customers arrive at the post office every $2\mathrm{.}0$ minutes on average with a standard deviation of $3\mathrm{.}1$ minutes.