A sum of Rs. 4500 amounts to Rs. 9000 in 4 years at the rate of simple interest. What is the rate of interest?  Choose the most appropriate option:  A) 37%  B) 25%  C) 35%  D) 6%  E) 20%
S.I. = (9000 - 4500) = Rs. 4500\   Rate = (100 * 4500) / (4500* 4)= 
<gadget id="calculator">(100 * 4500) / (4500* 4)</gadget>
<output>25</output>
25%   Answer: 25%
<result>B</result>
A sum of Rs. 4500 amounts to Rs. 9000 in 4 years at the rate of simple interest. What is the rate of interest?