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    Question

    The circumference of a circle is equal to the perimeter

    of a rectangle whose length and breadth are in ratio 5:4, respectively. If the area of the rectangle is 2420 cm2 , then find the radius of the circle.
    A 28 cm Correct Answer Incorrect Answer
    B 52.5 cm Correct Answer Incorrect Answer
    C 31.5 cm Correct Answer Incorrect Answer
    D 49 cm Correct Answer Incorrect Answer
    E 50.5 cm Correct Answer Incorrect Answer

    Solution

    Let the length and breadth of the rectangle be 5x cm and 4x cm, respectively
    According to the question,
    5x × 4x = 2420
    => x2 = 2420/20 = 121
    => x = 11
    Therefore, perimeter of the rectangle = 2 × (5x + 4x) = 198 cm
    Let the radius of the circle be ‘r’ cm
    According to the question,
    2πr = 198
    Or, r = 198 × (7/44) = 31.5 cm

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