Question

    If the radius of a cylinder is tripled and the height is

    halved, then what is the ratio between the new volume and the previous volume?
    A 4:5 Correct Answer Incorrect Answer
    B 3:2 Correct Answer Incorrect Answer
    C 5:2 Correct Answer Incorrect Answer
    D 9:2 Correct Answer Incorrect Answer

    Solution

    Old volume = πr2h New volume = π × R× H = π × (3r)2 × (h/2) Ratio of new volume to previous volume = π × (3r)2 × (h/2) ∶  πr2h Required ratio = (9/2) ×  πr2h ∶  πr2h = (9/2) ∶ 1 ∴ Required ratio = 9 ∶ 2

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