Standard deviation measures how far numbers in a data set are spread out from an average value. In investing, it is used as a measurement of portfolio volatility.

When you have the average production of three machines, it is easy to calculate the average or mean production. You just add ...

The reason we go through such a complicated process to define standard deviation is because this measure appears as a parameter in a number of statistical and probabilistic formulas, most notably ...

How to calculate standard deviation using the defining formula is explained. Discuss with students the need to go beyond averages to give a picture of what a sample is like. Consider real life ...