Question

The mean of $9,11,13,x,18,19$ is x. Find x.

Answer 1

$\Rightarrow$ The given numbers are $9,11,13,x,18,19$

$\Rightarrow$ Number of observation $=6$

$\Rightarrow$ Mean $=x$

$\therefore$ $\overline{x}=\frac{9+11+13+x+18+19}{6}$

$\therefore$ $x=\frac{70+x}{6}$

$\therefore$ $6x=70+x$

$\therefore$ $5x=70$

$\therefore$ $x=14$