Question

A certain sum of money becomes 5 times of itself in 25 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 = 25 years ∴ Simple Interest = Rs. (5x – x) = Rs. 4x Rate = [(4x × 100)/(x × 25)]% p.a. = 16% p.a. Now, Principal = Rs. x, Amount = Rs.2x, Rate = 16%p.a. Simple Interest= Rs. (2x − x)= Rs. x ∴ Time =(x × 100)/(x × 16) = 6.25 years.

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