**Calculation of Arithmetic
Mean & Standard Deviation**

**by**

**Short Method
from Assumed Mean**

Formulae:

Arithmetic Mean = Assumed Mean + ci; where c = fx' / (sum of the frequencies=N ), i= no. of entries in a class interval;

Standard Deviation = i*√ [(Σ **fx' ^{2}** / N) - c

Take Assumed Mean as the mid value corresponding to maximum frequency. In general, any value with the range of values can

be taken as Assumed Mean.