Math Question:Probability I don't know which formula to use or how to get started? Can Anyone help, PLEASE???

A New York Times survey of 3000 personal computer owners showed that 952 of them broke down during the first two years. In choosing among several computer suppliers, a purchasing agent wants to know the probability of a personal computer breaking down during the first two years. Use the survey results to estimate that probability. a) If a personal computer is randomly selected. What is the probability that it will break down during the first two years? b) If two personal computers are randomly selected, what is the probability that they will both break down during the first two years? c) If three personal computers are randomly selected, what is the probability that at least one of them breaks down during the first two years?

Math Question:Probability I don't know which formula to use or how to get started? Can Anyone help, PLEASE???
a: Chance of breakdown in two years 952/3000 or about 32%


b. .32 * .32 Each has to break down, multiply the probabilities together.


c. This is a reversal. You take the opposite question, of three computers, none breaking down, and subtract that probability from 1. Each computer has a 68% chance of surviving the two years. Thus, three computers all surviving is .68 * .68 * .68, or about .31 Subtract that from 1, and you get .69 -- There is a 69% chance that at least one computer will break down out of three.
Reply:For the overall probability, just divide 952 by 3000. The same applies to any individual computer. When you get to two computers, it's 952/3000 x 951/2999. John T has the correct answer for part (c). (Sorry, John, I mis-read the question.)