36.A sum of money invested at compound interest amounts to Rs. 800 in 3 years and to Rs. 840 in 4 years. The rate of interest per annum is
A. 2x1/2% B. 4%
C. 5% D. 6x2/3%
Answer:
S.I. on Rs.800 for 1 year =Rs[840 - 800]
= Rs.40
Rate =(100x40/800x1)%
= 5%
