CPU$-on-$Demand $(CPUD)$ offers real$-$time high$-$performance computing services. CPUD owns $1$ supercomputer that can $be$ accessed through the Internet. Their customers send jobs that arrive, $on$ average, every $6$ hours. The standard deviation $of$ the interarrival times $is5$ hours. Executing each job takes, $on$ average, $2$ hours $on$ the supercomputer and the standard deviation $of$ the processing time $is4\mathrm{.}6$ hours.

$On$ average, how long will $it$ take $to$ complete a job $(from$ the time $itis$ submitted $by$ the customer until the time $itis$ completed$)?$