Complement Rule

Apr 28, 2025the complement rule helps you find the probability of an event by using its opposite. The complement rule says the event's probability and its opposite add up to one. So the complement of an event is all the other outcomes (not the ones we want).

Jul 14, 2023the complement is useful when you are trying to find the probability of an event that involves the words “at least” or an event that involves the words “at most.” as an example of an “at. Oct 27, 2025the most common application of this rule is when we see probabilities that use the phrasing of "at least 1". Jan 1, 2026the complement rule states that for any two complements, a and b, the value of p (a) = 1 p (b).

In other words, subtract the complement you know from 1 to find the unknown complement. May 14, 2025discover how to use the complementary rule in probability with clear definitions, simple examples, and real-world applications. The complement, a c, of an event a consists of all of the outcomes in the sample space that are not in event a.

The probability of the complement can be found from the original event using the formula: Dec 22, 2025rather than listing all the possibilities, we can use the complement rule. Because we have already found the probability of the complement of this event, we can simply subtract that.

The complement rule is a fundamental concept in probability that states the probability of an event not occurring is equal to one minus the probability of the event occurring. The complement of an event is the probability of all outcomes that are not in that event. For example, if \ (a) is the probability of hypertension, where \ (p (a)=0.34), then the complement rule is: