\[Population{\text{ }}Variance{\text{ }}\sigma 2{\text{ }} = {\text{ }}\frac{{\left( {\sum {{{\left( {{X_i} - \mu } \right)}^2}} } \right)}}{N}\]
\[Standard{\text{ }}Deviation{\text{ }}\sigma {\text{ }} = {\text{ }}\sqrt {Variance} \]
\[Sample{\text{ }}Variance{\text{ }}{\sigma ^2}{\text{ }} = \frac{{\left( {\sum {{{\left( {{X_i} - \mu } \right)}^2}} } \right)}}{{N - 1}}\]
Where: