Question

    The compound interest (compounded annually) on Rs 8200 for 2 years at R% p.a is Rs 1722. Had the rate of interest been (R+10)% p.a what would have been the interest on the same sum of money for the same time (2 years)?

    A Rs 3608 Correct Answer Incorrect Answer
    B Rs 3860 Correct Answer Incorrect Answer
    C Rs 3456 Correct Answer Incorrect Answer
    D Rs 3342 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    CI = A + P 1722 = 8200 (1 + r/100)2 - 8200  9922 = 8200(1 + r/100)2  9922/8200 = (1 + r/100)2  121/100 = (1 + r/100)2  (11/10)2 = (1 + r/100)2    11/10 = (1 + r/100)   11/10 - 1 = r/100   1/10 = r/100   r = 10% p.a   New rate = 10 + 10 = 20% p.a   CI = 8200 (1 + 20/100)2 - 8200    = 8200 x 120% x 120% - 8200   = 11808 - 8200   = 3608

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