The government $311311$ hotline service is a non$$emergency phone number that people can call in many U$.$S$.$ and Canadian cities to find information about services, make complaints, or report problems like trash collection issues and potholes. Most cities perform analytics on call volumes to their call centers for purposes of maintaining adequate staffing and timely services. For the city of Chicago, the average number of $311311$ calls in the summer months is about $9\mathrm{.}79\mathrm{.}7$ per hour for the night shift $(11$:$00$ P$.$M$.$ to $7$:$00$ A$.$M$.).$ Suppose that the number of calls per time unit follows the Poisson distribution.