What is Relative Frequency?
When we run an experiment many times, we collect data about how often each outcome occurs. Relative frequency is the tool we use to turn those raw counts into something more meaningful — a proportion or percentage that tells us how often something happened compared to the total number of tries.
A single repetition of an experiment. For example, flipping a coin once or tossing a cone into the air once counts as one trial.
Any one of the possible results from a single trial. For example, when flipping a coin, the outcomes are heads and tails.
The number of times a particular outcome is observed across all trials.
The frequency of a particular outcome divided by the total number of trials. It can be expressed as a fraction, decimal, or percentage.
The relative frequencies of all outcomes from an experiment must always add up to 1 (or 100%). This is a useful check — if your relative frequencies don't sum to 1, you've made an error somewhere.
A Worked Example: Tossing a Plastic Cone
Imagine tossing a small plastic cone into the air 300 times and recording whether it lands on its side or its base. Here's what you might observe:
| Outcome | Frequency | Relative Frequency |
|---|---|---|
| Side | 203 | |
| Base | 97 | |
| Total | 300 | 1.000 |
From this experiment:
- The number of trials is 300
- The outcomes are side and base
- The frequency of side is 203; the frequency of base is 97
- The relative frequency of side is approximately 0.677
- The relative frequency of base is approximately 0.323
Notice that ✓ — the relative frequencies sum to 1, as expected.
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