Question

    Suresh earned an interest of Rs. 645 on principal amount

    of Rs. 2000 at some rate of compound interest in 2 years. How much more/less interest would he have earned on Rs. 2300 at the same rate of simple interest for the same duration?
    A Rs. 72 Correct Answer Incorrect Answer
    B Rs. 45 Correct Answer Incorrect Answer
    C Rs. 57 Correct Answer Incorrect Answer
    D Rs. 54 Correct Answer Incorrect Answer

    Solution

    Let, rate of interest be ‘r’% per annum So, 645 = 2000 × {(1 + r/100)2 – 1} 129/400 = {(1 + r/100)2 – 1} 529/400 = (1 + r/100)2 (23/20)2 = (1 + r/100)2 23/20 = 1 + r/100 3/20 = r/100, r = 15 So, simple interest earned = 2300 × 0.15 × 2 = Rs. 690 Required amount = 690 – 645 = Rs. 45

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