Question

6.27 Night watchmen carry an industrial flashlight 8 hr per night, 7 nights per week. It is estimated that on the average the flashlight is turned on about 20 min per -hr shift. The flashlight is assumed to have a constant failure rate of 0.08/hr while it is turned on and of 0.005/hr when it is turned off but being carried.

        (a) In working hours, estimate the MTTF of the light.

(b) What is the probability of the light’s failing during one 8-hr shift?

(c) What is the probability of its failing during one month (30 days) of 8-hr shifts?

Answer 1