Editing Arithmetic progression (section)

==Standard deviation==

The standard deviation of any arithmetic progression is

:<math> \sigma = |d|\sqrt{\frac{(n-1)(n+1)}{12}}</math>

where <math> n</math> is the number of terms in the progression and <math> d</math> is the common difference between terms. The formula is essentially the same as the formula for the standard deviation of a [[discrete uniform distribution]], interpreting the arithmetic progression as a set of equally probable outcomes.