For a frequency distribution standard deviation is computed by applying the formula
- A$\sigma = \sqrt {\left( {\frac{{\sum \,fd}}{{\sum \,f}}} \right) - \frac{{\sum \,f{d^2}}}{{\sum \,f}}} $
- B$\sigma = \sqrt {\frac{{\sum \,f{d^2}}}{{\sum \,f}} - {{\left( {\frac{{\sum \,f{d^2}}}{{\sum \,f}}} \right)}^2}} $
- C$\sigma = \sqrt {{{\left( {\frac{{\sum \,fd}}{{\sum \,f}}} \right)}^2} - \frac{{\sum \,f{d^2}}}{{\sum \,f}}} $
- D$\sigma = \sqrt {\frac{{\sum \,f{d^2}}}{{\sum \,f}} - {{\left( {\frac{{\sum \,fd}}{{\sum \,f}}} \right)}^2}} $
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