Question

The first, second and the fourth terms of a proportion are $6,18,75$, respectively. Find its third term.​

Answer 1

Let the third term be $x$

Since the numbers $6,18,x,\text{and}75$ are in proportion

$\Rightarrow$ $6:18=x:75$

$\Rightarrow$ $6\times 75=x\times 18$

($\because$ $\text{Product of extremes = Product of means}$)


$\Rightarrow$ $x=\frac{6\times 75}{18}=\frac{6\times 3\times 25}{6\times 3}=25$

$\therefore$ $x=25$

Hence, the value of $x$ $\text{is}$ $25$.