If rupee one produces rupees nine over a period of 40 years, find the rate of simple interest?	Choose the correct choice from the following.
A) 20 % B) 10 % C) 15 % D) 22 1/2% E) 21%
Explanation:   9 = (1*40*R)/100   R = 22 1/2 %   ANSWER IS 22 1/2%
<result>D</result>
If rupee one produces rupees nine over a period of 40 years, find the rate of simple interest?