Question

The algebraic sum of the deviations of $5$ observations measured from $15$ is $10$. Therefore the mean of this observation is _____.

• A. $15$
• B. $14.2$
• C. $17$
• D. $16.1$

Answer 1

The correct option is C $17$

Let the $5$ observations be $a,b,c,d$ and $e$.
So, the $5$ observations be $15+a,15+b....,15+e$.
The sum of these $5$ observations $=5\times 15+10$
The average of those $5$ observations is the sum divided by $5$, we get
$\frac{5\times 15+10}{5}=17$