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    Question

    A right circular cone is surmounted by a hemisphere. The

    base radius of the cone is equal to the radius of the hemisphere. The diameter of the hemisphere is 12 cm while the height of the cone is 8 cm. Find the cost of painting the compound object if it costs ₹25 to paint a cm².
    A ₹10,371 Correct Answer Incorrect Answer
    B ₹3,300 Correct Answer Incorrect Answer
    C ₹6,930 Correct Answer Incorrect Answer
    D ₹4,500 Correct Answer Incorrect Answer

    Solution

    Radius = 12 / 2 = 6 cm Since the right circular cone is surmounted on a hemisphere, the area of the base.   = 2 π ×62 = 72 π cm² Slant Height = √62 +√82 = 10 cm Hence, the total surface area of the cone is surmounted on the hemisphere. The curved surface area of the cone + the area of the base=π× 6 × 10 + 72π=132π Thus, the cost of painting the compound object = (25 × 132π) / π = 3300   The cost of painting the compound object is ₹3300.

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