A certain sum earns simple interest of Rs. 800 in 2 years at a certain rate of interest. If the same sum earns compound interest of Rs. 845 in the same period of 2 years, What must be the rate of interest?
Select:
A) 5% p.a.
B) 7.5% p.a.
C) 10% p.a.
D) 12.5% p.a.
E) None of these
Explanation:   Given: 800 = (P * R * 2) / 100   S.I. For 1 year = Rs. 400   Thus, (840 – 800) = S.I. on Rs. 400 for 1 year   40 = (400 * R * 1) / 100   R = 10% p.a.   ANSWER 10% p.a.
<result>C</result>
A certain sum earns simple interest of Rs. 800 in 2 years at a certain rate of interest. If the same sum earns compound interest of Rs. 845 in the same period of 2 years, What must be the rate of interest?