. At a supermarket 80% of the customers pay using December 28, 2016 By Essaypros . At a supermarket 80% of the customers pay using credit cards. Find the probability that in a randomly selected sample of 5 customers a) Exactly 2 customers pay using credit card. We Deliver Top Quality On Time As Promised! Ready to get started? Just click the button to be directed to a secure page so you can enter the details of your paper.