Mean (Average) Formula
Calculate the arithmetic mean with Mean = Σx / n.
The most common way to find the central value of a data set.
The Formula
Mean (x̄) = Σx / n
The mean is the sum of all values divided by the number of values. It is the most widely used measure of central tendency in statistics.
Variables
| Symbol | Meaning |
|---|---|
| x̄ | The mean (pronounced "x-bar") |
| Σx | The sum of all data values |
| n | The number of data values |
Example 1
Find the mean of: 12, 15, 18, 22, 33
Σx = 12 + 15 + 18 + 22 + 33 = 100
n = 5
Mean = 100 / 5
Mean = 20
Example 2
A student's test scores are: 85, 90, 78, 92, 88, 95. What is the average?
Σx = 85 + 90 + 78 + 92 + 88 + 95 = 528
n = 6
Mean = 528 / 6
Mean = 88 — The student's average test score is 88.
When to Use It
Use the mean formula when:
- You need a single number to represent a data set
- The data has no extreme outliers that would skew the result
- Calculating grade point averages, batting averages, or financial averages
- You need a baseline for further statistical calculations (like standard deviation)