## Statistics: Informed Decisions Using Data (4th Edition)

In this case, we are considering that it is possible that a selected patient visited the doctor for a blood pressure check and for urinalysis at the same time. So, the events "a patient visited the doctor for a blood pressure check" and "a patient visited the doctor for urinalysis" are not mutually exclusives (disjoint events). Then, we must use the General Addition Rule (page 273): $P(blood~pressure~check~or~urinalysis) = P(blood~pressure)+P(urinalysis)-P(blood~pressure~check~and~urinalysis)$