Multiple choice

If the height of cone is increased by 20% and radius is decreased by 30%. Then find the percentage increment/decrement on volume? किसी शंकु की ऊचाई 20 प्रतिशत बढ़ जाती है और त्रिज्या 30 प्रतिशत कम हो जाती है। तो उसका आयतन कितना प्रतिशत बढ़ेगा/घटेगा?

  1. 44.8%

  2. 48.8%

  3. 41.2%

  4. 52.2%
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C Correct answer
Explanation

Volume of cone = (1/3)πr²h. New height = 1.2h, new radius = 0.7r. New volume = (1/3)π × (0.7r)² × 1.2h = 0.588 × original volume. This is a decrease of 1 - 0.588 = 0.412 = 41.2%. The negative sign indicates decrease.

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