Asupermarket sells two flavors of cereal: a fruit flavor and a chocolate flavor. in a market survey, the event that a customer says he or she is willing to buy the fruit flavor is considered a success. records for the past 5 years show that an average of 71% of the customers buy the fruit-flavored cereal. if 20 cereal buying customers walk into the supermarket, what is the probability that at the most 19 of them will buy the fruit-flavored cereal?