Calculation of Arithmetic Mean & Standard Deviation
Short Method from Assumed Mean
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) - c2]
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.