For a frequency distribution, standard deviation is computed by

  • A
    $\sigma = \frac{{\sum f(x - \bar x)}}{{\sum f}}$
  • B
    $\sigma = \frac{{\sqrt {\sum f{{(x - \bar x)}^2}} }}{{\sum f}}$
  • C
    $\sigma = \sqrt {\frac{{\sum f{{(x - \bar x)}^2}}}{{\sum f}}} $
  • D
    $\sigma = \sqrt {\frac{{\sum f(x - \bar x)}}{{\sum f}}} $

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