Question

If the mean of $25$ observation is $27$ and each observation is decreased by $7$, what will be the new mean?

Answer 1

Let the sum of $25$ observations be x

Then $\frac{x}{25}=27$

So $x=27\times 25$

Each observation is increased by $7$

$\frac{x+25\left(7\right)}{25}=\frac{25\left(27\right)+25\left(7\right)}{25}=\frac{25(27+7)}{25}=34$.