Question

Find the value of x so that the given four numbers are in proportion:​
(iv)$4,x,6\text{and}18$.

Answer 1

Since the numbers $4,x,6\text{and}18$ are in proportion

$\Rightarrow$ $4:x=6:18$

$\Rightarrow$ $\frac{4}{x}=\frac{6}{18}$

$\Rightarrow$ $4\times 18=x\times 6$

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

$\Rightarrow$ $x\times 6=4\times (6\times 3)$

$\Rightarrow$$x=\frac{4\times 6\times 3}{6}=4\times 3$

$\therefore$ $x=12$

Hence, the value of $x$ $\text{is}$ $12$