Consider a single$-$server workstation that processes two types of jobs, type $1$ and type $2.$ Each job type arrives according

to a Poisson process with corresponding rates ra$1=6$ hr$1$ and ra$2=9$ hr$1$

$.$

These two arrival processes are independent from each other, and jobs are

processed according to a first$-$come$-$first$-$serve policy. The processing times

of the two job types are normally distributed with the corresponding distributions being N$1(5$min, $4$min$2$

$)$ and N$2(3$min, $1$min$2$

$).$