Maintenance crews arrive at the tool crib requesting a specific spare part according to Poisson distribution with parameter lambda = 2 . Three of such spare parts are normally kept on hand. If more than three orders take place, the crews should journey a considerable distance to central stores.
(a) On a given day, determine the probability that such a journey must be made?
(b) Determine the expected demand per day for spare parts?
(c) How many spare parts should be kept at hand so that the incoming crews can be serviced 95% of the time.