Question

What is the sub-duplicate ratio of 49:121?

• A. 7:11
• B. 9:25
• C. 9:81
• D. 7:5

Answer 1

The correct option is A

7:11

We know that, for a ratio a : b, sub-duplicate ratio is defined as the ratio of square of both the terms i.e. sub-duplicate ratio of a : b = $a^{\frac{1}{2}}:b^{\frac{1}{2}}$
$\therefore$ The sub-duplicate ratio of 49:121 is $\sqrt{49}:\sqrt{121}$ which is 7:11