Arithmetic mean
From ACT Wiki
Maths.
The arithmetic mean of a set of data is the simple average calculated by adding up all of the values and dividing by the total number of items.
For example, the arithmetic mean of 4%, 5% and 6% is
= ( 4% + 5% + 6% ) / 3
= 5%.
Also sometimes known as the Mean or the Expected value E[X].
Sometimes denoted by 'µ' - the Greek letter mu (or m).