Question

If the first three terms of a proportion are $9,8$ and $54$ respectively, find the fourth term.

Answer 1

Let, the fourth term be $\mathrm{X}$, then

$9˸8\colon\colon 54˸\mathrm{X}$

Product of extremes $=$ Product of means

$\begin{array}{rcl}9\times \mathrm{X}& =& 8\times 54\\ \mathrm{X}& =& \frac{8\times 54}{9}\\ \mathrm{X}& =& 48\end{array}$

Hence, the fourth term is $48$