Q. The algebraic sum of the deviation of 20 observations measured from 30 is 2. Then, mean of observations is
A) 28.5
B) 30.1
C) 30.5
D) 29.6
Explanation
(b)
Given that, $\sum_{i = 1}^{20}\left( x_{i} - 30 \right) = 2$
$\Rightarrow \ \ \sum_{i = 1}^{20}x_{i} - \sum_{i = 1}^{20}(30) = 2$
$\Rightarrow \ \ \ \overline{x} = \frac{20.30}{20} + \frac{2}{20}$
$= 30 + 0.1 = 30.1$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.