The manager of Ardmore Pharmacy knows that 25 percent of the customers entering the store buy prescription drugs,65 percent buy over-the-counter drugs,and 18 percent buy both types of drugs.What is the probability that a randomly selected customer will buy at least one of these two types of drugs?

Question

Quizplus · Accepted Answer

We can use the formula:

P(A or B) = P(A) + P(B) - P(A and B)

where A is the event of buying prescription drugs and B is the event of buying over-the-counter drugs.

P(A) = 0.25 
P(B) = 0.65 
P(A and B) = 0.18

So,

P(buying at least one of the two types of drugs) = P(A or B) = 0.25 + 0.65 - 0.18 = 0.72

Therefore, the probability that a randomly selected customer will buy at least one of these two types of drugs is 0.72, which corresponds to choice C.

The Manager of Ardmore Pharmacy Knows That 25 Percent of the Customers