Question

Find the fourth proportion for $2.8,14,3.5$

Answer 1

Let the fourth proportion be $x$

$\therefore 2.8:14::3.5:x$

$\Rightarrow \frac{2.8}{14}=\frac{3.5}{x}$

Cross multiply we get,

$\Rightarrow 2.8x=3.5\times 14$

$\Rightarrow 2.8x=49$

$\Rightarrow x=\frac{49}{2.8}$

$\Rightarrow x=17.5$