Video Crash Courses
Want to watch animated videos and solve interactive exercises about how to find the mean from a frequency table?
If you have organized your observations in a frequency table, you can find the mean directly from the table without writing it out as a long list of numbers. Here you’ll learn how.
Rule
You multiply every observational value by its frequency , add them together, then divide by the total number of observations:
Here’s the rule with a more theoretical approach:
Rule
Multiply every observational value by its frequency , then divide the sum of these values by the total number of observations.
Example 1
Below is an example of a table of frequencies. A class of 20 students had a test in mathematics. Their grades were as follows:
Grade | Frequency |
0 | 1 |
1 | 2 |
2 | 3 |
3 | 7 |
4 | 7 |
Total | 20 |
Find the mean grade.
The mean grade of the class was .
If you have a table of frequencies but only know the relative frequencies, you can find the mean in the following way:
Theory
Multiply each point with its relative frequency , where is the frequency and is the total number of observations, and add all these values together.
Example 2
A school of 974 students has given you a table containing relative frequencies of the grades its students have achieved in Latin, and have asked you to find the mean Latin grade.
Grade | Relative Frequency |
Total | 1 |