Complementary Events

Complementary events are pairs of events where only one can occur at a time. The complement of an event A is written as A', A^c, or A. It represents all possible outcomes that are not part of event A. For instance, when rolling a fair six-sided die, rolling an even number and rolling an odd number are complementary events.

The union of an event and its complement is the entire sample space.

The probability of an event and its complement always adds up to 1. P(Event) + P(Complement)=1