Mathematics - Statistics Question with Solution | TestHub

Let the observations be$x_1, x_2, ..., x_{50}$.

Given$\left(x_1-30\right)+\left(x_2-30\right)+.....+\left(x_{50}-30\right)=50$

$\Rightarrow x_1+x_2+.....+x_{50}=50+\left(30\times 50\right)=1550$

Now, Mean$=\frac{x_1+x_2+....+x_{50}}{50}=\frac{1550}{50}=31$.