Q. If the radius of a sphere is decreased by 20%, then its surface area decreases by:
✅ Correct Answer: (C)
36%
Explanation: Surface area ∝ r². (0.8)² = 0.64, hence decrease = 36%.
Explanation by: Mahesh Chandra
Surface area ∝ r². (0.8)² = 0.64, hence decrease = 36%.