Bob knows that the probability that a customer will make a purchase is 30%.

a) If we assume that customers behave independently, what is the probability that the next two customers Bob's store both make purchases?

b) Bob noticed that when two customers enter the store together, their purchases are not disjoint. In fact, there is a 20% chance they'll both make a purchase.

Use Rules of Probability, addition disjoint, and addition join methods to solve