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    Question

    A certain amount was deposited at compound interest of x%

    per annum, compounded annually. It grows to Rs. 6400 in 2 years and Rs. 9216 in 3 years. Determine the value of ‘x’.
    A 35 Correct Answer Incorrect Answer
    B 28 Correct Answer Incorrect Answer
    C 44 Correct Answer Incorrect Answer
    D 41 Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the principal amount = Rs. A

    We have, A × {1 + (x/100)}² = 6400

    And, A × {1 + (x/100)}³ = 9216

    So, 9216 ÷ 6400 = [A × {1 + (x/100)}³] ÷ [A × {1 + (x/100)}²]

    Or, 1.44 = {1 + (x/100)} = (100 + x)/100

    Or, 100 + x = 144

    So, x = 44

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