Question

Find the value of $x$ in each of the following proportions.

$x:2::5:4$

Answer 1

Here we know that if $a:b::c:d$ are in proportions,

then , $a\times d=b\times c$ -----------------------------$eq\left(1\right)$

Here we have $x:2::5:4$

so, $a=x,b=2,c=5,d=4$

by $eq\left(1\right)$ we have-

$$\begin{gathered} \Rightarrow x\times 4=2\times 5 \\ \Rightarrow 4x=10 \\ \Rightarrow x=\frac{10}{4} \\ \Rightarrow x=2.5 \end{gathered}$$

Hence for the value of $x=2.5$ the given $x:2::5:4$ are in proportions.