To help students with homework and to answer students' doubts in your operations management course GWU may consider starting a help desk every saturday staffed by your instructor. The working time of the help desk starts from $11$:$00$ am to $7$:$00$ pm$.$ Statistics show that students arrive at a rate of five per hour and the distribution is approximately Poisson. Assistance time averages $10$ minutes, distributed exponentially. Assume population and line length can be infinite and queue discipline is FCFS$.$

Help your instructor by finding out the how the desk is working?$($Show your work including all Excel formulas$)$