Question

Find the sub-duplicate ratio of 81:64?A.8:9B.4:9C.9:8D.7:8

Let us consider the given ratio 81:64 be a: b, where $a = 81$ and $b = 64$. As, we know that if the ratio is given in the form of a: b then the sub-duplicate ratio can be written as $\sqrt a :\sqrt b$ .Therefore,
$\Rightarrow \sqrt {81} :\sqrt {64} = 9:8$
Note: The sub-duplicate ratio of a: b is $\sqrt a :\sqrt b$ , whereas the duplicate ratio of a: b is ${a^2}:{b^2}$.