If the radius of a sphere is reduced by 50%, by what percentage does its surface area decrease?
A50%
B60%
C75%
D80%
Explanation
Surface area is proportional to r^2. If new r = 0.5r, new area = (0.5)^2 * original area = 0.25 * original area. Decrease = 100% – 25% = 75%.
Exam Relevance
- Topic: Geometry & Mensuration
- Subtopic: Spheres
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