New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    The area of a circle is nine times its circumference

    (numerically). What is the diameter of the circle?
    A 27 units Correct Answer Incorrect Answer
    B 10 units Correct Answer Incorrect Answer
    C 36 units Correct Answer Incorrect Answer
    D 21 units Correct Answer Incorrect Answer

    Solution

    ATQ,

    Circumference = 2 × π × r

    Area = π × r²

    Let radius = r units

    Then, π × r² = 9 × 2 × π × r

    ⇒ r² = 18r

    ⇒ r = 18

    Diameter = 2 × 18 = 36 units

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