Question

How to calculate step deviation

Answer 1

by a+ £fixi/ £fi ×h method

Answer 2

hay!!
by this formula


Example :-
1) Apply Step - Deviation method to find arithmetic mean of the following frequency distribution.
variate51015202530Frequency204375677245
Solution: 
Let the assumed mean be A = 20 and h = 5.

Variate (xi)Frequency (fi)Deviation= di = xi - 20ui = (xi - 20 )/ 5fi ui520-15-3-601043-10-2-861575-5-1-75206700025725172304510290N = Σ fi = 322-59
N = 322, A = 20 , h = 5 and Σ fi ui = - 59
use the formula
⇒ Mean = 20 + 5 ( - 59 / 322) 
⇒ Mean = 20 – 0.91
∴ Mean = 19.09
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I hope it's help you