Statistics

Variance of the following continuous frequency distribution is

$$ \begin{array}{cc} \hline \text { Class Interval } & \text { Frequency } \\ \hline 0-4 & 1 \\ \hline 4-8 & 2 \\ \hline 8-12 & 2 \\ \hline 12-16 & 1 \\ \hline \end{array} $$