Helping the step deviation method find the arithmetic mean of the… - Vidyadip

Question

Helping the step deviation method find the arithmetic mean of the distribution:

Variable (x)	5	10	15	20	25	30	35	40	45	50
Frequency(f)	20	43	75	67	72	45	39	9	8	6

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Answer

Let the assumed Mean be A = 25 and h = 5.

We have,
N = 384, A = 25, h = 5 and $\sum f_i u_i=-214$
Mean $\overline{( X )}= A + h \left(\frac{1}{ N } \sum f_i u_i\right)$
$=25+5 \times\left(\frac{-214}{384}\right)$
= 25 - 2.786
= 22.214.

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