Height of a cone is increased by 20% where as its radius is decreased by 25%. find the percentage change in its volume. एक शंकु की ऊचाई 20% बढ़ा दी गयी जबकि इसकी त्रिज्या 25% कम कर दी गयी इसके आयतन में प्रतिशत बदलाव ज्ञात कीजिये।
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32.5% increase/वृद्धि
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32.5% decrease/कमी
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27.5/increase/वृद्धि
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27.5/decrease/कमी
B
Correct answer
Explanation
Original volume = (1/3)πr²h. New height = 1.2h, new radius = 0.75r. New volume = (1/3)π(0.75r)²(1.2h) = (1/3)π × 0.5625r² × 1.2h = 0.675 × (1/3)πr²h. This is 67.5% of original volume, meaning a 32.5% decrease. The calculation is straightforward percentage change.