A flashlight contains two batteries each having an MTTF of 5

A flashlight contains two batteries each having an MTTF of 5 operating hours (assume CFR).

a) What is the probability of the battery failure occurring within the first 2 hours operations?

b) If the failed batteries are replaced immediately, what is the probability of more than one failure occuring in the first 5 hours of operation?

Solution

X - no of hours it operates is Poisson with mean = 5

a_ P(X<2) = 0.0404

b) P(X>1) =0.9596