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 and time in years be in the ratio 1:4, then the rate of interest is:  Choose the correct choice from the following answers
A) 4 1/2 %.	B) 3 1/2 %.	C) 2 1/2 %.	D) 2 3/4 %.	E) 4 3/4 %.
Explanation :   Let sum = x. Then, S.I. = x/4   Let rate = R% and time = R years.   [x * R * 4R / 100] = x / 4 ? R^2 = 25/4   R = 5/2 = 2 1/2.   Hence, R = 2 1/2 %.   Answer : 2 1/2 %.
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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 and time in years be in the ratio 1:4, then the rate of interest is: