The complement of an event is the set of all outcomes in a sample space that are not included in the event. It is denoted as $E'$ or $E^c$ where $E$ is the event.
5 Must Know Facts For Your Next Test
The probability of the complement of an event $P(E')$ is calculated as $1 - P(E)$.
If an event $E$ is certain to happen, then its complement $E'$ has a probability of 0.
If an event $E$ is impossible, then its complement $E'$ has a probability of 1.
The sum of the probabilities of an event and its complement always equals 1: $P(E) + P(E') = 1$.
The concept of complements is critical for understanding mutually exclusive events, where two events cannot both occur.