SSC GD 2023 PYQ — Question 53

The correct answer is option 2 i.e. 2√7.

Calculations:

We know that,

For, a : b :: c : d

⇒ a/c = b/d

So,

The fourth proportional to √6, √8, and √21 = (√8 × √21)/√6 = 2√7