We consider a level-2 IT service desk with 2 staff members. Each staff member can handle one service request in 4 working hours on average. Service times are exponentially distributed. Requests arrive at a mean rate of one request every 3 hours according to a Poisson process. What is the average time between the moment a service request arrives at this desk and the moment is fulfilled?

(Show all the formulas and computations - since Lq (avg number of jobs in queue) is complex to calculate assume that it is = 1.02 (requests).)