### 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:**

### 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 |