Question

If $\mu$ is the mean of a distribution, then $\sum f_i(y_i-\mu )$ is equal to

• A. mean deviation
• B. standard deviation
• C. None of these

Answer 1

$\sum f_i(y_i-\mu )=\sum f_i{y}_i-\mu \sum f_i=\mu \sum f_i-\mu \sum f_i=0[\because \mu =\frac{\sum f_i{y}_i}{\sum f_i}]$