What is the probability that the student checks out a fiction or non-fiction book?

Question

A student goes to the library. The probability that she checks out a fiction book is 0.45, a work of non-fiction book is 0.28, and both fiction and non-fiction book is 0.10. What is the probability that the student checks out a fiction or non-fiction book?

Answer 1

The formula is:

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

Therefore, the probability is 0.45 + 0.28 - 0.10 = 0.63