Question

Find the value of $x$ so that the given four numbers are in proportion.

$x,10,15and30$

Answer 1

We know that if four numbers $a,b,candd$are in proportion.

then $a\times d=b\times c$ …………………………….$eq\left(1\right)$

so, here in $x,10,15and30$

$a=x,b=10,c=15,d=30$

the by $eq\left(1\right)$ we have,

$$\begin{gathered} \Rightarrow x\times 30=10\times 15 \\ \Rightarrow 30x=150 \\ \Rightarrow x=\frac{150}{30} \\ \Rightarrow x=5 \end{gathered}$$

Hence the value of $x=5$ for which the given four numbers $x,10,15and30$ are in proportions.