Mathematics for IGCSE & O level - Probability (Section 6 - No. 19)
When are two events considered mutually exclusive?
When they both have the same chance of occurring.
When they cannot both occur at the same time.
When the outcome of one event affects the outcome of the other.
When the probability of one event is 1 minus the probability of the other.
Explication
Mutually exclusive events cannot happen at the same time.