Relative Frequency Theory

The relative frequency theory of probability holds that if an experiment is repeated an extremely large number of times and a particular outcome occurs a percentage of the time, then that particular percentage is close to the probability of that outcome.

For example, if a machine produces 10,000 widgets one at a time, and 1,000 of those widgets are faulty, the probability of that machine producing a faulty widget is approximately 1,000 out of 10,000, or 0.10.