Question

The mean of 30 observations is 18. If each observation is increased by 2 , then find the mean of new observations.

Answer 1

The mean of $20$ observation is $25$

$\therefore$ Sum of $20$ observations $=20\times 25=500$

$\Rightarrow$ New sum of $20$ observations after increasing each observation by $2$ $=(2\times 20)+500=40+500=540$

$\Rightarrow$ Required mean $=\frac{540}{20}=27$