2023 · Q58
The surface area of a cube is increased by 25%. If p is the percentage increase in its length, then which one of the following is correct?
Elementary MathematicsMensuration
- A16
- B14
- C12
- D10
Explanation
Surface area scales as the square of the side: (1 + p/100)² = 1.25, so p = 100(√1.25 − 1) ≈ 11.8%. Among the given options the correct choice is 12% (C). The stored key (D, 10%) is wrong and has been fixed.