Question

Two pumps connected in parallel fail indepen- dently of each other on any given day. The proba- bility that only the older pump will fail is .10, and the probability that only the newer pump will fail is .05. What is the probability that the pumping system will fail on any given day (which happens if both pumps fail)?

Answer 1

Answer: 0.145

Explanation:

Since,

the Probability of the older pump failing P(fail older) = 0.10

The probability of the newer pump failing P(fail newer) = 0.05

Therefore,

The Probability of the older pump not failing P(not fail older) = 1 - 0.1

P(not fail older) = 0.9

Also,

The probability of the newer pump not failing P(not fail newer) = 1 - 0.05 = 0.95

The probability of the pumping system failing = P(not fail older)* P(not fail newer) = 0.9*0.95

P(not fail system)= 0.855

Therefore,

The probability that the pumping system will fail = 1 - P(not fail system) = 1 - 0.855 = 0.145

The probability that the pumping system will fail one day is 0.145