A marketing research firm advises a new client that approximately 15% of all persons sent a sweepstakes

Question:

A marketing research firm advises a new client that approximately 15% of all persons sent a sweepstakes offer will return the mailing. Suppose the client sends out 10,000 sweepstakes offers.
a. What is the probability that fewer than 1,430 of the mailings will be returned?
b. What is the probability that more than 1,600 of the mailings will be returned?