Question

The fourth proportional to $4,6,8$Is What.

Answer 1

Proportions and their properties:

Let the fourth proportion be $\mathrm{x}$

$\Rightarrow 6:8::4:\mathrm{x}$

Product of mean proportional$=$ product of extreme proportions
$\begin{array}{rcl}6\times 8& =& 4\times \mathrm{x}\\ \mathrm{x}& =& \frac{6\times 8}{4}\\ \mathrm{x}& =& 6\times 2\\ \mathrm{x}& =& 12\end{array}$

Hence, the fourth proportional is $12$