Probability Terms

Probabilities are represented by a number between 0 and 1, and can be written as a decimal, fraction or percent. A probability of 0 is called an impossible event. A probability of 1 is called a certain event. A sample space is the set of all possible outcomes of a probability experiment. It is helpful when determining the probability of an event to first organize the sample space.

Example 1 When rolling a die, what is the probability of rolling a number less than 7?

This event is certain and has a probability of 1.

Example 2 When rolling a die, what is the probability of rolling a 7?

This event is impossible and has a probability of 0.

To learn more about probability, watch the video below.