Question:
In the formula $\bar{x}=a+h\left(\frac{\Sigma f_{i} u_{i}}{\Sigma f_{i}}\right)$, for finding the mean of grouped frequency distribution $u_{i}$ is equal to
(a) $\frac{x_{i}+a}{h}$
(b) $h\left(x_{i}-a\right)$
(c) $\frac{x_{i}-a}{h}$
(d) $\frac{a-x_{i}}{h}$
Solution:
(c) Given, $\bar{x}=a+h\left(\frac{\Sigma f_{i} U_{i}}{\Sigma f_{j}}\right)$
Above formula is a step deviation formula.
$u_{i}=\frac{x_{i}-a}{h}$