A department store polled 600 shoppers regarding whether or not they made a purchase, and whether or not they were pleased with the service they received. Of those who made a purchase, 113 were happy with the service, and 140 were not. Of those who made no purchase, 226 were happy with the service, and 121 were not. Use probability rules (when appropriate) to find the probability of the following events: Find the probability that a shopper made no purchase, given that they were happy with the service.