Question

If the probability of hearing a "yes" to a campaign contribution drive is 0.07, and 250 requests are made, what is the probability of getting at least 20 positive responses?

Answer 1

You need to use the binomial distribution. First calculate the probabilities of getting 0, 1, 2, 3, 4, .............., 18, 19 positive responses and add them. Then subtract the total from 1.

Answer 2

http://mathworld.wolfram.com/BinomialDistribution.html