Consider a single$-$server workstation where the server experiences preemptive nondestructive outages according to the model that was discussed in class. Jobs arrive with a rate of $10$ jobs per hour and the nominal mean processing time $($i$.$e$.,$ without considering the delays due to the outages$)$ is $5$ minutes. The average duration of a single outage is $10$ minutes. What is the maximal rate for the occurrence of the experienced outages that maintains the stability of the station? Please, express your result in outages per hour.

Remark: As a more general point, it is worth$-$noticing that the time considered in this analysis is the "operational $-$ or functional $-$ time" of the server, i$.$e$.,$ the time that it is working on jobs, since when it is idle, the counting process that generates the outages, is stopped.