What is the formula of variance by step deviation method

Dear Student, 

We use the following formula to calculate standard deviation using step deviation method.

$S\tan dard deviation = \sqrt{\frac{{\sum }_{}f{d}_x^I}{N}- {\left(\frac{{\sum }_{}f{d}_x^I}{N}\right)}^2} \times h$
Variance is nothing but Standard Deviation squared. Hope that this clears your doubt. 

Feel free to contact us in case you have any other queries. 

Regards