Question

The sum of deviatomns of 50 observation is 30 is 50

Answer 1

ARITHMETIC Mean -

For the values x1, x2, ....xn of the variant x the arithmetic mean is given by

\bar{x}= \frac{x_{1}+x_{2}+x_{3}+\cdots +x_{n}}{n}

in case of discrete data.

-

Standard Deviation -

In case of discrete frequency distribution

\sigma = \sqrt{\frac{\sum f_{i}x_{i}^{2}}{\sum f_{i}}-\left ( \frac{\sum f_{i}x_{i}}{\sum f_{i}} \right )^{2}}

-

It should be bonus as deviations means \left | x_{i}-30 \right | and not x_{i}-30.

Otherwise,

Given, \sum_{i=1}^{50}(x_{i}-30)=50

=>\sum x_{i}=30 (50)+50

=>\frac{\sum x_{i}}{50}=31