Relative frequency
Calculate relative frequency in Grade 9 statistics. Divide each category frequency by total count to find proportions, interpret data distributions, and compare datasets of different sizes.
Key Concepts
Property In an experiment, the number of times an event happens divided by the total number of trials is the relative frequency of that event. It can be expressed as a fraction, decimal, or percent. $$\text{Relative Frequency} = \frac{\text{Number of times event occurs}}{\text{Total number of trials}}$$.
Explanation This fancy term just asks, "How often did this one thing happen compared to everything else?" It is a way to see the proportion of a specific outcome. You just divide the count of what you are looking for by the total count of all data points. This helps you compare a part of your data to the whole.
Examples In a bag of 20 marbles, 5 are blue. The relative frequency of blue is $\frac{5}{20} = \frac{1}{4} = 0.25 = 25\%$. In a class of 30 students, 6 have birthdays in March. The relative frequency is $\frac{6}{30} = \frac{1}{5} = 0.20 = 20\%$.
Common Questions
What is relative frequency and how is it calculated?
Relative frequency = frequency / total observations. It shows what fraction of the total each category represents. For 15 out of 60 students: 15/60 = 0.25.
How do you convert relative frequency to a percentage?
Multiply the relative frequency by 100. A relative frequency of 0.25 becomes 25%. This makes data interpretation easier for communication.
What is the difference between frequency and relative frequency?
Frequency is the raw count of occurrences. Relative frequency expresses that count as a proportion of the total, enabling comparison across datasets of different sizes.