Relative Frequency and Probability Distributions

This lesson covers relative frequency in more detail and introduces probability distributions — a way of listing all possible outcomes of an experiment alongside their probabilities. These topics are part of the AQA GCSE Mathematics specification and build on the earlier lessons on experimental probability and expected outcomes.

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Relative Frequency Recap

Relative frequency is the proportion of times an event occurs in an experiment:

Relative frequency = frequency of event / total number of trials

Relative frequency provides an estimate of the true probability. It is especially useful when outcomes are not equally likely.

Worked Example 1

A biased spinner is spun 200 times. The results are:

Colour	Frequency
Red	48
Blue	72
Green	80
Total	200

Calculate the relative frequency for each colour:

Colour	Frequency	Relative Frequency
Red	48	48/200 = 0.24
Blue	72	72/200 = 0.36
Green	80	80/200 = 0.40
Total	200	1.00