Which term is the probability of an event not happening?

Which term is the probability of an event not happening?

• A. Complement of an event
• B. Probability
• C. Theoretical probability
• D. Sample Space

Answer: (A)

The idea being tested is the complement of an event. The probability of an event not happening is called its complement. Since either the event occurs or it does not, the two possibilities add up to 1. So if the event has probability p, the probability that it does not happen is 1 − p. This is a handy way to find the “not happening” chance without counting everything again. Other terms aren’t describing this specific idea. Probability is the general likelihood of any event. Theoretical probability is a way to calculate likelihood under a model, not the particular “not happening” probability. The sample space is the set of all possible outcomes, not a probability itself.

The idea being tested is the complement of an event. The probability of an event not happening is called its complement. Since either the event occurs or it does not, the two possibilities add up to 1. So if the event has probability p, the probability that it does not happen is 1 − p. This is a handy way to find the “not happening” chance without counting everything again.

Other terms aren’t describing this specific idea. Probability is the general likelihood of any event. Theoretical probability is a way to calculate likelihood under a model, not the particular “not happening” probability. The sample space is the set of all possible outcomes, not a probability itself.