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The variance of the following frequency distribution is
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The correct answer is:
161.1
Given frequency distribution
$\because \quad N=\Sigma f_i=70$
$\therefore$ variance $\left(\sigma^2\right)=\frac{1}{N} \Sigma f_i x_i^2-\left[\frac{1}{N} \Sigma f_i \cdot x_i\right]^2$
$=\frac{1}{70}(42150)-\left[\frac{1}{70}(1470)\right]^2=\frac{4215}{7}-441$
$=\frac{4215-3087}{7}=\frac{1128}{7}=161.1$
$\because \quad N=\Sigma f_i=70$
$\therefore$ variance $\left(\sigma^2\right)=\frac{1}{N} \Sigma f_i x_i^2-\left[\frac{1}{N} \Sigma f_i \cdot x_i\right]^2$
$=\frac{1}{70}(42150)-\left[\frac{1}{70}(1470)\right]^2=\frac{4215}{7}-441$
$=\frac{4215-3087}{7}=\frac{1128}{7}=161.1$
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