A sum of Rs. 3000 amounts to Rs. 9000 in 4 years at the rate of simple interest. What is the rate of interest?  Choose the correct choice from the following options.
A) 75%
B) 90%
C) 55%
D) 60%
E) 50%
S.I. = (9000 - 3000) = Rs. 6000   Rate = (100 * 6000) / (3000* 4)= 
<gadget id="calculator">(100 * 6000) / (3000* 4)</gadget>
<output>50</output>
50%   Answer: 50%
<result>E</result>
A sum of Rs. 3000 amounts to Rs. 9000 in 4 years at the rate of simple interest. What is the rate of interest?