Phoenix water is provided to approximately 1.4 million people who are served through more than 362,000. All accounts are metered and billed monthly. The probability that an acoount has an error in a month is 0.001, and accounts can be assumed to be independent.

(a) What are the mean and standard deviation of the number of account errors each month?

(b) Approximate the probability of fewer than 340 errors in a month.

(c) Approximate a value so that the probability that the number of errors exceeds this value is 0.1

(d) Approximate the probability of more than 425 errors per month in the next three months. Assume that results between moths are independent.