Compute some probabilities for Facebook friends. Suppose that 60% of your Facebook friends became your friends because you asked them to be. You select a simple random sample of 20 of your friends.
(a) What is the probability that 12 of them became your friend because you asked them?
(b) What is the probability that between 9 and 15 of them became your friends because you asked them? Include the possibilities of 9 and 15 in your calculations.
(c) What are the mean and the standard deviation of the number who became your friends because you asked them?