Question

In each of the following question, select the related number from the given alternatives.
$42$ $:$ $20$ $:$ $:$ $64$ $:$ $?$

• A. $32$
• B. $33$
• C. $34$
• D. $31$

Answer 1

The correct option is D $31$

In the first pair ,

$\frac{42}{2}-1=20$

Similarly, for next pair

$\frac{64}{2}-1=31$

So, $20$ and $42$ are related the same way $31$ and $64$ are related.

$\therefore$ The correct answer is $31$. $\left[D\right]$