1) A sum of money on compound interest amounts to Rs. 10,648 in 3 years and Rs. 9680 in 2 years. The rate of interest per annum is A) 5% B) 10% C) 15% D) 20% E) 25% Answer: Option BExplanation:Let Sum be P and rate be R% per annum. Then P(1+R100)2 =9680 ---------------------- (1) P(1+R100)3 =10648 -----------------------------(2) Divide equ. (2) by (1) ⇒1+R100 =106489680 R100 =110 = 10%