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