2.5 Mutually Exclusive Events

Justify why two events are mutually exclusive (or disjoint) using joint probability.

• The probability that events A and B both will occur, sometimes called the joint probability, is the probability of the intersection of A and B. Joint probability is defined as P ()ABintersect or P (AB∩ .)
• Two events are mutually exclusive, or disjoint, if they cannot occur at the same time. This means that if two events are mutually exclusive, then P ()AB∩ =0 .