Mutually Exclusive Events

What are Mutually Exclusive Events?

Two events are mutually exclusive if they cannot both happen. Consider the possible outcomes of one roll of a die. The events:

1. x = an even number”
2. x = 3 are mutually exclusive
3. cannot both happen on the same roll

Example of mutually exclusive events:

P(A or B) = P(A) + P(B) − P(AB).

When events A and B are mutually exclusive,

P(AB)=0, so P(A or B) = P(A) + P(B).