The Outcome (A or B) sometimes is called the union of A and B. The union event occurs if either Outcome A or Outcome B (or both) occurs. Suppose that both A and B can happen at the same time (i.e., their areas overlap in a Venn diagram). Show that P (A or B) = P (A) + P (B) – P (A and B). Use a Venn diagram to explain. Why is this result consistent with the second requirement that probabilities add up?