Probability is defined as the ratio of the number of desired outcomes (what you want to happen) to the number of total possible outcomes (what could possibly happen).

Probability = Number of Desired Outcomes over Total Number of Possible Outcomes Number of Desired Outcomes Total Number of Possible Outcomes

A simple event is when one event occurs. A compound event is when two or more events occur in a sequence. If any event does not affect the outcomes of the other events, then the events are independent events.

To determine the probability of independent events, multiply the probabilities of each event occurring by itself.