1) A sum of money invested at compound interest amounts in 3 years to Rs.2400 and in 4 years to Rs.2520. The rate of interest is A) 5% B) 6% C) 10% D) 12% E) 8% Answer: Option AExplanation:$S.I.$ for $1$ year $=2520-2400$ $=120$ $P=2400$ Rate % $=\frac{120\times 100}{2400\times 1}$ = 5%
