Question

First, second and fourth terms of a proportion are respectively $5.2,3.9$ and $3$. Find its third term.

Answer 1

Let $5.2:3.9::x:3$

$\frac{5.2}{3.9}=\frac{x}{3}$

$x=3\times \frac{5.2}{3.9}$

$x=4$