A repairman for refrigerators is sent to a city only when three or more request have been placed. The requests follow the Poisson distribution with mean of 0.25 per week for city with population of 100,000. Your city haves a population of 800,000.
(a) Determine the probability that repairman is required after one-week period?
(b) If you're the first one in the city to place an request, Determine the probability that you've to wait more than two weeks from time you place your order till a repairman is sent?