Statistics
Arithmetic mean
Add every value and divide by how many there are. Uses all the data, so extreme values pull it towards them.
The Formula
mean = sum / n
Add every value and divide by how many there are. Uses all the data, so extreme values pull it towards them.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| sum | Sum | same unit as the data | Total of every value in the list. |
| n | Count | count | How many values the list contains. |
| mean | Mean | same unit as the data | The arithmetic average. |
What Each Symbol Means
sumsame unit as the data
Sum
Total of every value in the list.
ncount
Count
How many values the list contains.
meansame unit as the data
Mean
The arithmetic average.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate the average (mean, median and mode) page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate The Average (Mean, Median And Mode), filed under Math. Every number the guide produces comes from substituting into this one line.