Question

Find the value of “?” in the below expression.
\[5:30::8:?\]

Answer 1

Hint: In this problem, first we need to convert the given proportion into two equivalent fractions. Next, solve the obtained fractions to find the value of the missing number.

Complete step-by-step answer:
Consider, the missing number be \[x\].
Now, the given ratio can be written as shown below.
\[\begin{gathered}
  \,\,\,\,\,\,5:30::8:x \\
   \Rightarrow \dfrac{5}{{30}} = \dfrac{8}{x} \\
\end{gathered}\]
Now, use cross multiplication to find the value of \[x\] as shown below.
\[\begin{gathered}
  \,\,\,\,\,\,5x = 30 \times 8 \\
   \Rightarrow 5x = 240 \\
   \Rightarrow x = \dfrac{{240}}{5} \\
   \Rightarrow x = 48 \\
\end{gathered}\]
Thus, the value of the missing number is 48.

Note: Proportion is used to describe the two fractions as equal. A proportion can be written in two ways, either as two equal fractions or using a colon. The fundamental rule to find the value of missing fraction is cross multiplication.