Question

Find the mean of the following frequency distribution using assumed mean method:

• A. 17.7
• B. 18.8
• C. 19
• D. 19.9

Answer 1

The correct option is B 18.8

Suppose we assume ‘17’ as assumed mean, then the deviation of other observations from the assumed mean is given in table.

Sum of frequencies = 40
$\sum f_i$ = 40

Sum of the $f_i\times d_i$ products = (-72) + (-18) + 0 + 66 + 96 = 72
$\sum f_i{d}_i$ = 72


$Mean=A+\frac{\sum f_i{d}_i}{\sum f_i}$

$=17+\frac{72}{40}$

$=17+\frac{72}{40}$

$=17+1.8=18.8$

Thus, 18.8 is the mean of the given frequency distribution.