Venn Diagram for Addition Rule

Addition Rule:

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

Example. If the probabilities are, respectively, 0.7, 0.8 and 0.6 that a person vacationing in Washington, D.C. will visit the Capitol building, the Smithsonian Institution, or both, what is the probability that a person vacationing there will visit at least one of these buildings?

Solution. 0.7 + 0.8 - 0.6 = 0.9