The maintenance staff of a large office building regularly replaces
The maintenance staff of a large office building regularly replaces fluorescent ceiling lights that have gone out. During a visit to a typical floor, the staff may have to replace several lights. The manager of this staff has given the following probabilities to the number of lights (identifed by the random variable Y) that need to be replaced on a floor:
(a) How many lights should the manager expect to replace on a floor?
(b) What is the standard deviation of the number of lights on a floor that are replaced?
(c) If a crew takes six lights to a floor, how many should it expect to have left after replacing those that are out?
(d) If a crew takes six lights to a floor, find the standard deviation of the number of lights that remain after replacing those that are out on a floor.
(e) If it takes 10 minutes to replace each light, how long should the manager expect the crew to take when replacing the lights on a floor?
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