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    Question

    A certain sum of money becomes 5 times of itself in 20

    years at simple interest. In how many years does it become double of itself at the same rate of simple interest?
    A 12.5 years Correct Answer Incorrect Answer
    B 5 years Correct Answer Incorrect Answer
    C 10 years Correct Answer Incorrect Answer
    D 6.25 years Correct Answer Incorrect Answer

    Solution

    Let the principal = Rs. x, Amount = Rs. 5x, Time = 20 years ∴  Simple Interest = Rs. (5x – x) = Rs. 4x Rate = [(4x × 100)/(x × 20)]% p.a. = 20% p.a. Now, Principal = Rs. x, Amount = Rs.2x, Rate = 20%p.a. Simple Interest = Rs. (2x − x)= Rs. x ∴  Time = (x × 100)/(x × 20) = 5 years.

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