If the simple interest on a certain sum of money for 8 years is one–fifth of the sum, then the rate of interest per annum is
Select:
A) 4.1%
B) 7%
C) 2.5%
D) 2.8%
E) 3%
Explanation:   Let the Principal(P) be x   Then, Simple Interest(SI) = x/5   Time(T) = 8 years   Rate of interest per annum(R) = (100×SI)/PT   = (100 × (x/5)/(x × 8) = 20/8= 
<gadget id="calculator">20/8</gadget>
<output>5/2 = around 2.5</output>
2.5%   Answer: Option 2.5%
<result>C</result>
If the simple interest on a certain sum of money for 8 years is one–fifth of the sum, then the rate of interest per annum is