Question

    A sum of money doubles itself in 5 years at simple interest. In how many years will it become 5 times itself at the same rate of interest?

    A 15 years Correct Answer Incorrect Answer
    B 20 years Correct Answer Incorrect Answer
    C 25 years Correct Answer Incorrect Answer
    D 30 years Correct Answer Incorrect Answer

    Solution

    Let the principal be P and the rate of interest be R. According to the question, 2P=P+ (P×R×5)/100 P = PR/20 R=20% For the amount to become 5 times the principal: 5P=P+ (P×20×T)/100 4P=(P×20×T)/100 T=20 = 20 years

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