Simple interest on a certain sum at a certain annual rate of interest is 1/4 of the sum. If the numbers representing rate percent is 5time of years , then the Time is:  Choices:
A) 6 1/2 years.
B) 5 1/2 years.
C) 4 1/2 years.
D) 2 1/2 years.
E) 3 1/2 years.
Explanation :   Let sum = x. Then, S.I. = x/4   Let Time =N and R = 4 N.   [x * N * 4N / 100] = x / 4? N^2 = 25/4   N = 5/2 = 2 1/2 years.   Hence,n = 2 1/2 years.   Answer : 2 1/2 years.
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Simple interest on a certain sum at a certain annual rate of interest is 1/4 of the sum. If the numbers representing rate percent is 5time of years , then the Time is: