12-7 Theoretical and Experimental Probability

Objective

To find theoretical and experimental probabilities

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In the Solve It, spinning red and choosing the right envelope are desired outcomes. An outcome is the result of a single trial, such as spinning a wheel. The sample space is all the possible outcomes. An event is any outcome or group of outcomes. The outcomes that match a given event are favorable outcomes.

Here is how these terms apply to rolling an even number on a number cube.

Essential Understanding The probability of an event, or P(event), tells you how likely it is that the event will occur. You can find probabilities by reasoning mathematically or by using data collected from an experiment.

In the number-cube example above, the outcomes in the sample space are equally likely to occur. When all possible outcomes are equally likely, you can find the theoretical probability of an event using the following formula.

You can write the probability of an event as a fraction, a decimal, or a percent. The probability of an event ranges from 0 to 1.

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