Question

he manager of a grocery store reports that there is a 12 percent chance that a customer buys apples during a shopping trip, a 5 percent chance that a customer buy apples and carrots, and a 17 percent chance that a customer buys apples or carrots.

What is the probability of a customer buying carrots?

1.4 percent
5.0 percent
10.0 percent
11.4 percent

Answer 1

Use P(A ∪ C) = P(A) + P(C) − P(A ∩ C). So

P(C) = P(A ∪ C) − P(A) + P(A ∩ C) = 0.17 − 0.12 + 0.05 = 0.10,

or 10.0 percent.