Question $1$ to Question $6$ is based on this problem.

Boot Barn sells cowboy boot and western wear through catalogs and the web. Customers can phone in orders at any time day or night, $7$ days a week. During the $1$ am to $9$ am shift, a single sales rep handles all calls. During this time, calls arrive at a rate of $14$ per hour following a Poisson distribution. It takes the sales rep an average of four minutes to process each call. The variability in service times is approximately exponentially distributed. All calls received while the sales rep is busy are placed in a queue.

Which of the following statement regarding this problem is not true?