Question

Find the third proportional to $36,18$

Answer 1

Let the required third proportional be $x$
$\therefore 36,18,x$ in continued proportion
$\Rightarrow 36:18=18:x$
$\Rightarrow 36\times x=18\times 18$
$\Rightarrow x=\frac{18\times 18}{36}$
$\Rightarrow x=9$
$\Rightarrow$ Required proportional is $9$