5. It has been determined that the population average household income in a county is / = 70,000, and the population standard deviation o = 5,000. Let X be the average income in a random sample of 60 households from that county. (a) What is the mean and the standard deviation of X? (b) Find the probability that X will be larger than 71,000. (c) What is the probability that the total income in the sample of 60 is less than 4,140,000