The probability of an event occurring is the definition of which concept?

• A. Probability
• B. Odds
• C. Frequency
• D. Expectation

Answer: (A)

Probability is the measure of how likely an event is to occur. It’s defined as the ratio of favorable outcomes to all possible outcomes in a well-defined experiment, typically ranging from 0 (impossible) to 1 (certain). The statement described matches this exact idea: it names the likelihood of an event happening.

Odds, in contrast, compare favorable to unfavorable outcomes (a ratio), not the probability itself. Frequency refers to how often an event is observed in a set of trials, which is an empirical estimate, not the formal definition. Expectation (or expected value) is the long-run average outcome you’d anticipate if the experiment were repeated many times, weighted by probabilities.