Question

Find the value of $a$ in the following proportion.

$4:7::a:49$

Answer 1

In a proportion $p:q::r:s$,

We know that, $p\times s=q\times r$

Thus, in the given proportion $4:7::a:49$, we have

$$\begin{gathered} \Rightarrow a\times 7=49\times 4 \\ \Rightarrow a=\frac{49\times 4}{7}=7\times 4=28 \end{gathered}$$

Hence, $a=28.$