1. For certain personal tax returns, the IRS will compute the amount to refund a taxpayer. Suppose the Chicago office of the IRS processes an average of five returns per hour that require a refund calculation.

a. What probability distribution applies to this situation?

b. What is the probability that the IRS processes exactly three refunds in a particular hour that requires a refund calculation?

c. What is the probability the IRS does not compute a refund on any return in an hour?

d. What is the probability the IRS processes at least one return in a particular hour that requires a refund calculation?