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    Question

    A certain sum of money becomes 4 times of itself in 15

    years at simple interest. In how many years does it become double of itself at the same rate of simple interest?
    A 5 yrs. Correct Answer Incorrect Answer
    B 4 yrs. Correct Answer Incorrect Answer
    C 3 yrs. Correct Answer Incorrect Answer
    D 7 yrs. Correct Answer Incorrect Answer
    E 6 yrs. Correct Answer Incorrect Answer

    Solution

    Let the principal = Rs. x, Amount = Rs. 4x, Time = 15 years ∴ Simple Interest = Rs. (4x – x) = Rs. 3x Rate = [(3x × 100)/(x × 15)]% 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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