Multiple choice

If the radius of a cone is doubled and height is decreased by 50% find the percentage change in volume of cone.

  1. 80%

  2. 100%

  3. 200%

  4. 150%

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Original cone volume V = (1/3)πr²h. New radius = 2r, new height = 0.5h. New volume V' = (1/3)π(2r)²(0.5h) = (1/3)π(4r²)(0.5h) = 2×(1/3)πr²h = 2V. Change = V' - V = V. Percentage change = (V/V)×100 = 100% increase.

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