Question

The first, second and fourth terms of a proportion are $9,20and40$ respectively. Find its third term.

Answer 1

Find the third term:

Let, the third be $x$.

Given that $9,20,xand40$ are in proportion.

So, $9:20::x:40$

$\Rightarrow \frac{9}{20}=\frac{x}{40}$

$\Rightarrow 20x=9\times 40$

$\Rightarrow x=\frac{9\times 40}{20}$

$\Rightarrow x=18$

Hence, the third term is $18$.