An artificial number that we create to represent a set of numbers.
The arithmetic mean or average (called mean) of a1, a2, a3, . . ., an is given by:
(a1+a2+a3+. . .+an)/n
If the set of numbers a1, a2, a3, . . ., an occur with frequencies f1, f2, f3, . . ., fn, then the arithmetic mean is given by:
(f1a1+f2a2+f3a3+ ... +fnan)/(f1+f2+f3+ ... +fn)
The geometric mean of a1, a2, a3, . . ., an is given by: