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    Question

    Area of a rectangle is equal to the total surface area

    of a hemisphere having volume 13718 cm³ . Find the perimeter of the rectangle if its length is 125% more than its breath. (Take π = 3)
    A 234 cm Correct Answer Incorrect Answer
    B 247 cm Correct Answer Incorrect Answer
    C 143 cm Correct Answer Incorrect Answer
    D 130 cm Correct Answer Incorrect Answer

    Solution

    Let, the radius of the hemisphere be ‘r’ cm. So according to question: 2/3 × 3 × r3 = 13718 r3 = 6859 r = 19 So, the total surface area of the hemisphere = 3 × π × 19² = 3 × 3 × 19² = 3249 cm² Let the breadth of the rectangle be ‘x’ cm So the length of the rectangle = 2.25x cm According to question: x × 2.25x = 3249 x² = 1444 x = 38 So the breadth of the rectangle = 38 cm Length of the rectangle = 38 × 2.25 = 85.5 cm So the perimeter of the rectangle = 2 × (85.5 + 38) = 247 cm

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