How to calculate standard deviation sample?

Formula for standard deviation sample calculation is:

SD = sqrt ((∑ (x - m) ²) / (n - 1)),

where x stays for each value in the data set, m stays for mean of all values in the data set, and n stays for the number of values in the data set.

For example: Find the sample standard deviation for the set of numbers: 10, 11, 11, 12, 12.

First we will find mean of all avlues: m = (10 + 11 + 11 + 12 + 12) / 5 = 11.2

SD = sqrt ((1.2² + 0.2² + 0.2² + 0.8² + 0.8²) / (5 - 1)) =

= sqrt (2.8 / 4) = √0.7 = 0.837