Written by the Fiveable Content Team โข Last updated September 2025
Written by the Fiveable Content Team โข Last updated September 2025
Definition
Mutually exclusive events are events that cannot occur at the same time. If one event happens, the other cannot.
5 Must Know Facts For Your Next Test
If $A$ and $B$ are mutually exclusive, then $P(A \cup B) = P(A) + P(B)$.
The intersection of mutually exclusive events is always zero: $P(A \cap B) = 0$.
Mutually exclusive is different from independent; mutually exclusive events are dependent because the occurrence of one affects the probability of the other.
In a Venn diagram, mutually exclusive events do not overlap.
For any two events to be mutually exclusive, their combined probability cannot exceed 1.
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Related terms
Independent Events: Two events are independent if the occurrence of one does not affect the probability of the other.