Question

The algebraic sum of deviations of ten observations about 15 is 70.The mean is

• A. 22
• B. 25
• C. 20
• D. none of these

Answer 1

Answer: (A)

22

Given $\sum _{i=1}^{10}(x_i-15)=70$
$\Rightarrow \sum _{i=1}^{10}{x}_i-\sum _{i=1}^{10}15=70\Rightarrow \sum _{i=1}^{10}{x}_i=70+15\times 10=220$
Thus mean of the given distribution is $=\frac{\sum _{i=1}^{10}{x}_i}{10}=22$