Hour of Math · SS1 · Unit SSSP2

Mean Deviation and Variance of Grouped Data — Extended Tables

Calculate the mean deviation $MD = \frac{\Sigma f|x_m - \bar{x}|}{\Sigma f}$, the variance with the long method $S^2 = \frac{\Sigma f(x_m - \bar{x})^2}{\Sigma f}$, and the variance with the shortcut $S^2 = \frac{\Sigma f x_m^2}{\Sigma f} - (\bar{x})^2$, confirming both methods agree.

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