How many jobs are there in the queue portion of the CPU on average, E  Ncpu Q  ?

For the interactive system in Figure 6.14, suppose that we are given the following information: mean user think time = 5 seconds expected service time at device i = .01 seconds utilization of device i = .3 utilization of CPU = .5 expected number of visits to device i per visit to CPU = 10 expected number of jobs in the central subsystem (the cloud shape) = 20 expected total time in system (including think time) per job = 50 seconds. How many jobs are there in the queue portion of the CPU on average, E  Ncpu Q  ?