The arithmetic mean or average (called mean) of a₁, a₂, a₃, . . ., a_n is given by:

(a₁+a₂+a₃+. . .+a_n)/n

If the set of numbers a₁, a₂, a₃, . . ., a_n occur with frequencies f₁, f₂, f₃, . . ., f_n, then the arithmetic mean is given by:

(f₁a₁+f₂a₂+f₃a₃+ ... +f_na_n)/(f₁+f₂+f₃+ ... +f_n)

The geometric mean of a₁, a₂, a₃, . . ., a_n is given by:

(a₁×a₂×a₃×...×a₃)^1/n