Your store is interested in learning more about customers' purchasing patterns and how they relate to the frequency of store visits. The probability that a customer's visit will result in a purchase is 0.35. The probability that a customer has been to the store within the past month is 0.20. Of those who did not buy anything, 12% had been there within the past month. a. Find the probability of making a purchase given that the customer had been to the store within the past month. b. What percent of customers are frequent shoppers, defined as making a purchase and having been to the store within the past month?