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).