Example
Ex 1:
The difference between C.I and S.I on a sum of Rs. 625 at 10% p.a for 1 year is
Sol:
|
Amount at C.I
|
= |  |
| = |  |
|
| = |  |
|
| = | Rs. 687.50 | |
|
Amount at S.I
|
= |  |
| = |  |
|
| = | |
|
| = | Rs. 687.50 | |
| Difference between amount at C.I and S.I in 1 year | ||
| = | Rs. 687.50 – Rs. 687.50 | |
| = | 0 | |
Ex 2:
Calculate the amount at compound interest on Rs. 20000 for 3 years when the rates of interest for successive years are 6%, 8% and 10% respectively.
Sol:
| Given P = 20000 | ||
|
r1
|
= | 6% |
|
r2
|
= | 8% |
|
r3
|
= | 10% |
|
A
|
= |  when rates are
different |
|
A
|
= |  |
| = |  |
|
| = |  |
|
| = |  |
|
| = | Rs. 25185.60 | |
Ex 3:
A sum lent on C.I become Rs. 2420 in 2 years and Rs. 2662 in 3 years. Find the sum.
Sol:
|
Amount in 3 years
|
= | Rs. 2662 |
|
Amount in 2 years
|
= | Rs. 2420 |
|
C.I for third year
|
= | Rs. 2662 – Rs. 2420 |
| = | Rs. 242 | |
|
Principal for third year
|
= | Rs. 2420 |
|
T
|
= | 1 year |
 R |
= |  |
|
A
|
= |  |
|
2420
|
= |  |
|
2420
|
= |  |
|
2420
|
= |  |
| = |  |
|
|
P
|
= |  |