Question

A store owner decides to put a coupon in the Sunday newspaper. The advertising firm she works believes that at least 20% but no more than 30% of people who shop at his store will use the coupon. The paper circulates 50,000 copies of the Sunday paper and ALL her customers get the Sunday paper. She believes that everyone shopping at her store receives the Sunday paper. What is the probability that 50% or more of the customers in a single day will have a coupon?