Question

If the arithmetic mean of $7,9,11,13,x,21$ is $13$, find the value of $x$.

Answer 1

Find the value of $x$

Given that value of mean $=13$.

$\mathrm{Mean}\left(\overline{X}\right)=\frac{\mathrm{Sum}\mathrm{of}\mathrm{terms}}{\mathrm{Number}\mathrm{of}\mathrm{terms}}$

Mean $\left(\overline{X}\right)=\frac{7+9+11+13+x+21}{6}$

$\therefore 13=\frac{61+x}{6}$

$\Rightarrow 78=61+x$

$\Rightarrow x=78-61$

$\therefore x=17$

Hence, the value of $x$ is $17$.