A) A firm operates a truck on a job contracting basis. The job requests is Poisson distributed with a mean request rate of 1.5 per day. The average service time is 3.75 hours and is exponentially distributed. Determine all the performance measures and the probability that there are more than three jobs in the system.
B) The AB Company has a single '93turret lathe'94 as a key work center on its factory floor. Jobs arrive randomly at this work center at a mean rate of two per day. The processing time to perform each job has an exponential distribution with a mean of 0.25 day. Because the jobs are bulk, those not being worked on are currently being stores in a room some distance from the machine. However, to save time in fetching the jobs, the production management is proposing to add enough in-process storage space next to the turret lathe to accommodate three jobs, in addition the one being processed. ) Excess jobs will continue to be stored temporarily in the distant room.) Under this proposal, explain what proportion of the time will this storage space next the turret lath is adequate to accommodate all waiting jobs?}