Which statement best defines probability?

Which statement best defines probability?

• A. The long-run ratio of the number of times an outcome occurs to the number of times the experiment is conducted.
• B. The long-run ratio of the number of times an outcome does not occur to the number of times the experiment is conducted.
• C. The percentage of games won by a player.
• D. The average amount of money in the drop box.

Answer: (B)

Probability is the long-run frequency with which a specific outcome occurs when you repeat the experiment many times. It is defined as the ratio of the number of times that outcome happens to the total number of trials conducted. In other words, as you perform more and more trials, the observed proportion of occurrences tends to settle at a fixed value. If you think in terms of the complement—the event that the outcome does not occur—that probability would be the complement: one minus the probability of the event itself, not the probability of the event you’re focusing on. Other options describe related ideas but aren’t the standard definition: the percentage of games won reflects past results or observed outcomes, not the fundamental likelihood of a single trial; and the average money in the drop box is unrelated to the chance of a particular outcome.

Probability is the long-run frequency with which a specific outcome occurs when you repeat the experiment many times. It is defined as the ratio of the number of times that outcome happens to the total number of trials conducted. In other words, as you perform more and more trials, the observed proportion of occurrences tends to settle at a fixed value.

If you think in terms of the complement—the event that the outcome does not occur—that probability would be the complement: one minus the probability of the event itself, not the probability of the event you’re focusing on. Other options describe related ideas but aren’t the standard definition: the percentage of games won reflects past results or observed outcomes, not the fundamental likelihood of a single trial; and the average money in the drop box is unrelated to the chance of a particular outcome.