Understand the subject
How are average, sum, and count connected?
Average, sum, and count are three views of the same relationship. Know any two and you can solve the third—provided the count is a real positive whole number.
The relationship
The defining relationship
Sum is the total of all values; count is how many values there are; average is the equal-share value.
See the idea
One identity, three possible solves
cover one quantity to solve it
Worked example
Recover the total
An average of 12 across 8 values means the total is 12 × 8 = 96. In reverse, 96 divided by 8 gives 12.
Interpret with care
Choose the relationship that fits
A result of 2.4 for a count is not a valid count of observations. Also, a sum of 0 and average of 0 do not identify one unique positive count.
For a side-by-side view of the classical means, use the Mean Comparison Calculator.
