Many people like to shop in person, then make their purchase later, online. Of all the shoppers, it was found that 30% of shoppers make purchases when they physically enter a store. Some retailers offer promotions to attempt to track customers purchasing using the process of looking then ordering online. Retailers started to offer customers, when leaving the building without making a purchase, a discount code to use for online purchases. It was found that there's a 9% chance of a person making a purchase using the code later.

A. What is the probability that a shopper who enters the building will not make any purchases?

B. Retailers noticed when two shoppers enter the building to shop together (the purchases are not disjoint), there is a 20% chance they both will make a purchase. What is the probability that at least one of them makes a purchase?