If the difference between the compound interest and simple interest on a sum of 5% rate of interest per annum for three years is Rs. 36.60, then the sum is = ?
A. Rs. 8000
B. Rs. 8400
C. Rs. 4400
D. Rs. 4800
Answer: Option D
Solution (By Examveda Team)
Note : In such type of questions to save your valuable time follow the given below methodRate % = 5%
Effective Rate of CI for 3 years = 15.7625%
Effective Rate of SI for 3 years = 5 × 3 = 15%
According to the question
$$\eqalign{ & \left( {15.7625 - 15} \right)\% \,{\text{of sum}} {\text{ = Rs. 36}}{\text{.60}} \cr & {\text{0}}{\text{.7625% of sum}} {\text{ = Rs. 36}}{\text{.60}} \cr & {\text{Sum = }}\frac{{36.60}}{{0.7625}} \times 100 \cr & \,\,\,\,\,\,\,\,\,\,\,\, = {\text{Rs. }}4800 \cr} $$

effective rate ci iz by 2x+x2/100 formula
(105)^3/1000 =15.7625 for effective rate of CI
Difference between CI and SI =[PR×R(300+R)]÷(1000000)
Using this formula we can find the answer
Formula for Effective rate of compound interest ={[(1+(r/n)]^n}-1
= {[1+(5/100×3)]^3}-1
= 15.7625.
How to find the effective rate of CI?