The proportion of the total data represented by the frequency of each class is called relative frequency.
Relative frequency = frequency of the class ÷ total frequency
The sum of the relative frequencies is always 1 (or 100%).
📘 Example ①
If there are 20 data values and the frequency of a certain class is 5, find the relative frequency.
Answer:5 ÷ 20 = 0.25 (25%)
If there are 20 data values and the frequency of a certain class is 5, find the relative frequency.
Answer:5 ÷ 20 = 0.25 (25%)
💡 Key Point
- Relative frequency = frequency ÷ total
- Sum of relative frequencies = 1
- Use relative frequency when comparing data sets with different totals
Practice Problems
- There are 40 data values, and the frequency of the class 60-70 is 8. Find the relative frequency of this class.
Answer and Explanation
- Answer:0.2 (20%). 8÷40=0.2.