\[\boxed{\mathbf{314.}}\]
\[S = 96;\ \ N = 20;\ \ S_{кв.} = 478.\]
\[\ \overline{x} = \frac{S}{N} = \frac{96}{20} = \frac{48}{10} = 4,8.\]
\[Дисперсия:\]
\[\frac{S_{кв}.\ - 2\overline{x}S + 20{\overline{x}}^{2}}{20} =\]
\[= \frac{478 - 2 \cdot 4,8 \cdot 96 + 20 \cdot {4,8}^{2}}{20} =\]
\[= \frac{17,2}{20} = \frac{86}{100} = 0,86.\]
\[Ответ:0,86.\]