Multiple choice

If the radius of a sphere is reduced by 20%, what percent of the surface area is reduced ? यदि गोले की त्रिज्या को 20% कम कर दिया जाये तो पृष्ठीय क्षेत्रफल में कितने प्रतिशत की कमी हुई ?

  1. 16%

  2. 36%

  3. 44%

  4. 24%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Surface area of sphere = 4πr². New radius = 0.8r (20% reduction). New surface area = 4π(0.8r)² = 0.64 × 4πr². Reduction = 1 - 0.64 = 0.36 = 36%. Option B is correct. The surface area reduces by 36%, not 16%, 24%, or 44%.

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