Question

A repair shop repairs an average of 4.5 machines per hour. Let X be the time (in hours) before the first machine is repaired.(a) What is the probability that a repair time exceeds 4 hours?(b) What is the average time (in hours) it takes to repair the first machine?(c) The conditional probability that a repair takes at least 6 hours, given that it takes more than 4 hours?

Answer 1

a) P(X>4)=e-4*4.5 =1.523*10-8 ~ 0.0000

b) 1/4.5 =0..2222 Hours

c) P(X>6|X>4) =P(X>2)=e-2*4.5 =0.000123

Explanation: