What is probability?

• A. The likelihood that a particular event will occur.
• B. The number of times an event occurs in a trial.
• C. The probability of rolling an even number on a fair die.
• D. The certainty that an event will occur.

Answer: (A)

Probability is the likelihood that a particular event will occur. It describes how probable something is, not how many times it happens or how certain we are in all cases. It can be written as a decimal, fraction, or percent between 0 and 1 (0% to 100%). The statement captures the general idea of probability. Saying it’s the number of times an event occurs is describing frequency, not probability. Saying it’s the certainty of an event would imply probability equals 1, which only happens for events that must happen. Describing a specific example, like the chance of rolling an even number on a fair die, shows how probability is applied, but isn’t the definition itself.