Mutually Exclusive Events
Definition
Two events that cannot occur simultaneously — the occurrence of one precludes the occurrence of the other. For mutually exclusive events: P(A∩B) = 0, and P(A∪B) = P(A) + P(B).
Example
"Getting a Head or a Tail on a single coin toss are mutually exclusive events. P(H or T) = P(H) + P(T) = 1/2 + 1/2 = 1."