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    Question

    Two cones X and Y of are melted together to form a

    cylinder of height 48 m. The height of cones X and Y are in the ratio of 3:2 respectively and the radius of cone X is 5/6 of the radius of cone Y. The curved surface area of cylinder is 2112 cm 2 .Which of the following can be determined?I: Radius of cylinderII: Total surface area of cone XIII: Relation between radius and height of cone.
    A Only II Correct Answer Incorrect Answer
    B Only III Correct Answer Incorrect Answer
    C Only I and III Correct Answer Incorrect Answer
    D Only II and III Correct Answer Incorrect Answer
    E All I, II and III Correct Answer Incorrect Answer

    Solution

    Curved surface area of cylinder = 2112 cm 2

    2 * 22/7 * R * 48 = 2112

    R = 7 cm

    Let height of cone X and Y are '3h' cm and '2h' cm respectively and radius of cone X and Y are '5r' cm and '6r' cm respectively.

    1/3 * π [25r 2  *3h + 36r 2  *2h] = π*7*7*48

    r 2 h = 48

    I: Radius of cylinder = 7 cm

    II: Total surface area of cone X cannot be determined.

    III: Relation between radius and height of cone = r 2 h = 48 cm 3

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