Average is a term that is used, mis-used and often overused. Typically, many individuals refer to average when they really mean the arithmetic average (mean). Average can mean the mean, the median, and the mode, it can refer to a geometric mean and weighted averages.

Although most people use the term average for this type of calculation:

Four tests results: 15, 18, 22, 20

The sum is: 75

Divide 75 by 4: 18.75

The 'Mean' (Average) is 18.75

(Often rounded to 19)

The truth of the matter is that the above calculation is considered the arithmetic mean, or often referred to as the mean average.