Question

I cant figure this out, please explain.

A certain airplane has (2) independent alternators to provide electrical power. The probablility that a given alternator will fail on a 1 hr flight is .02.
What is the probability that (a) both will fail (b) neither will fail (c) one or the other will fail? Show steps...

Answer 1

The probability that both will fail is 0.02 x 0.02. The probability that neither will fail is (1-0.02)*(1-0.02) = 0.98 x 0.98. The probability that one or the other will fail is (2 x 0.02 x 0.98). Why? Because there are two situations to consider here: Alternator A fails but alternator B doesn't, and alternator B fails but alternator A doesn't. The probability of each of them is the same, i.e. 0.02 x 0.98. Check that the sum of the probabilities of all three scenarios adds up to 1, because they ought to.

Answer 2

I used your example for my other problem and I was able to figure it out. Thank You!!!!