Question

Mean of eight observations is $25$. If one observation $11$ is excluded, find the mean of the remaining

Answer 1

$\overline{x}=25$

$n=8$

$\overline{x}=\frac{\sum x}{n}$

$\sum x=\overline{x}n=25\times 8=200$

If $one$ observation is removed, then new $\sum y=\sum x-11=189.$

Now, $n=7$ [$\because One$ observation is removed.]

$\therefore \overline{y}=\frac{\sum y}{n}=\frac{189}{7}=27$