Question 1.
Example: P=20000 Rs. , r= 10%. t= 2 years, A=?
Solution:
Question 2.
Example: What will be the compound interest on Rs. 12000 after 3 years at the rate of 10% per annum?
Solution:
![](https://2.bp.blogspot.com/-AFFND-VDSTA/WaaqaV-kkYI/AAAAAAAABlQ/LkksVygVch4tu0hypi60m-qYhiMtML8vgCK4BGAYYCw/s400-rw/5.PNG)
![](https://3.bp.blogspot.com/-7FTjlZxInPE/Waaqfo7I0aI/AAAAAAAABlY/95QFCnQ17z0_SSWd07ulmWUMREA3gKK8ACK4BGAYYCw/s1600-rw/6.PNG)
Example: A sum of money becomes double itself in 5 years at compound interest. In how many years will it become 8 times of itself?
Solution:
![](https://3.bp.blogspot.com/-FpVRM1vHL30/WaaqmKNGNnI/AAAAAAAABlg/vLZNtI38wesR3PmAOPHxWa62HpsZxpfiQCK4BGAYYCw/s400-rw/7.PNG)
![](https://1.bp.blogspot.com/-lnyWbX9IdOc/WaaqrbFLrRI/AAAAAAAABlo/uStzEWPR74gpqvQsYtz6_wYpuZEMl4n-wCK4BGAYYCw/s1600-rw/8.PNG)
Example:
![](https://4.bp.blogspot.com/-0vMF_EfCPiI/WaarBDj3G1I/AAAAAAAABlw/e_HIlmMglvA89WMYj5AMGPQg02eXShMDQCK4BGAYYCw/s320-rw/9.PNG)
Solution:
![](https://3.bp.blogspot.com/-iIQJPzoQmR4/WaarES2lEnI/AAAAAAAABl4/Map7ZJyv0gUKlEnRwfMgfYNv0MmJCFpeQCK4BGAYYCw/s320-rw/10.PNG)
Convert r% into fraction (a/b)
![](https://1.bp.blogspot.com/-e95Wjc36eXg/WaarJ56xRkI/AAAAAAAABmA/_pPOIMB5c0UupfM2pc6XQCwnfyj0K5D5ACK4BGAYYCw/s320-rw/11.PNG)
Example: A man borrowed Rs.8,400 at 10% p.a. CI. He pays equal annual instalment and clear off his debts in 2 yrs. Find the instalment?
Solution:
![](https://2.bp.blogspot.com/-Kze6FZlQVoM/WaarfKwF8tI/AAAAAAAABmI/art6viTDcOE6Wqu0EM1XQcT9FRaXKEuHgCK4BGAYYCw/s320-rw/12.PNG)
Convert r% into fraction (a/b)
![](https://2.bp.blogspot.com/-XwULg7PnmxE/WaarkGMp8wI/AAAAAAAABmQ/-Stf7cScaSE6Z-xyu2YFVUlZPdpn_dNNgCK4BGAYYCw/s1600-rw/13.PNG)
Example: A man borrowed Rs.397950 at 6% p.a. CI. He pays equal annual instalment and clear off his debts in 3 yrs. Find the instalment.
Solution:
![](https://4.bp.blogspot.com/-bqce2QVX3DU/WaarveXqsCI/AAAAAAAABmY/6N4QHTp7f0UCkbgNLoL6aTokbDOPUDqxgCK4BGAYYCw/s1600-rw/14.PNG)
![](https://4.bp.blogspot.com/-t5NrqztBJ1E/Waar33ysldI/AAAAAAAABmo/1r1nPTGhQT0tgoTsT_JJYmoVLYQIdaMhACK4BGAYYCw/s400-rw/15.PNG)
Example: If the difference between S.I. and C.I. for 2 years on certain money is 4 Rs. The rate of interest is 8% per annum then find the money.
Solution:
![](https://2.bp.blogspot.com/-VXVffP-0Rlw/Waar6bq0GMI/AAAAAAAABmw/eqChmCULIegPb2dxdAHJXxVbaVeHlKdCwCK4BGAYYCw/s400-rw/16.PNG)
![](https://2.bp.blogspot.com/-8Ri8-SueEh0/Waar-OS94wI/AAAAAAAABm4/FGjrc-fkhCkA9PVz11t1159TcvlJV-6ugCK4BGAYYCw/s320-rw/17.PNG)
Example: If the difference between S.I. and C.I. for 3 years on certain money is 31 Rs. The rate of interest is 10% per annum then find the money.
Solution:
![](https://1.bp.blogspot.com/-C4-Cr_ZJ9Bo/WaasBalnObI/AAAAAAAABnA/a5Fc7z3ZTEAuCLfcBqqnVi91A1PvKihCwCK4BGAYYCw/s320-rw/18.PNG)
Solution:
Solution:
Question 3.
If a sum of money becomes n1 times itself at compound interest in t1 years then after t2 sum will be:Example: A sum of money becomes double itself in 5 years at compound interest. In how many years will it become 8 times of itself?
Solution:
Question 4.
Example:
Solution:
Question 5.
Calculation of instalment for 2 years:Convert r% into fraction (a/b)
Example: A man borrowed Rs.8,400 at 10% p.a. CI. He pays equal annual instalment and clear off his debts in 2 yrs. Find the instalment?
Solution:
Question 6.
Calculation of instalment for 3 years:Convert r% into fraction (a/b)
Example: A man borrowed Rs.397950 at 6% p.a. CI. He pays equal annual instalment and clear off his debts in 3 yrs. Find the instalment.
Solution:
Question 7.
If the difference between C.I. and S.I. for 2 years is given, then Principal:Example: If the difference between S.I. and C.I. for 2 years on certain money is 4 Rs. The rate of interest is 8% per annum then find the money.
Solution:
Question 8.
If difference between C.I. and S.I. for 3 years is given, then Principal:Example: If the difference between S.I. and C.I. for 3 years on certain money is 31 Rs. The rate of interest is 10% per annum then find the money.
Solution:
Question 9.
A sum of money invested at compound interest amounts to 800Rs. in 3 years and Rs. 882 in 5 years. What is the rate of interest?Solution:
Question 10.
When r% is given p.a. and CI has to be calculated half-yearly or quarterly basis:Yearly | factors | r% (per annum) | Time (n years) |
---|---|---|---|
Half yearly | 6 months= (6/12)=1/2 |
Factor ×r%= r/2% | 2n |
Quarterly | 3 months= (3/12)=1/4 | 1/4 ×r% = r/4% | 4n |
9 months | 9 months= (9/12)=3/4 | 3/4× r%= 3r/4% | 4n/3 |
8 months | 8 months= (8/12)= 2/3 | 2/3× r%= 2r/3% | 3n/2 |