## Compound Interest Part 1

Problem 1: Find the successive discount of  % and 40%

Solution:

Fractional value of  % is

Fractional value of 40% is

8        5

5         3

8*5=40

5*3=15

The result is 8 and 3

8 is the marked price and 3 is the S.P

8-3=5

%

There is a successive discount of  %

Problem 2: Find the successive increase of % and %

Solution:

Fraction for % is

Fraction for % is

9         10

8           9

Cancel common terms and the result is 8 and 10

4-5=1

%

There is a successive increase of 25%

Note: when there is a successive decrease it is discount, When there is a successive increase it is compound interest.

## Compound Interest Part 2

Based on part 1 we will solve some problems in compound interest.

Problem 1: Find the principle and compound interest if the rate of interest is 10% and time is 2years and amount is 2420?

Solution:

R=10%

Time =2 years

Amount=2420

Principle=?

C.I=?

The fraction of 10% is

10      11

10      11

10*10=100

11*11-121

Let 100 as a principle

121 as amount

121-100=21 is C.I

121———>2420

100———->?

121———->2420

21————–>?

Principle =2000 and C.I=420

Problem 2: P=?, T=2 years,=%, %,CI=480

Solution :

Convert % into fraction i.e

Convert % into fraction i.e

9      10

8       9

Cancel the common term 9 and the result is 8 and 10

Here 4 is the principle and 5 is the amount

4-5=1 is C.I

1———->480

4———–> ?

is the principle.

## Compound Interest Part 3

Problem 1: P=?, R=%, T=2years, C.I-S.I=40,C.I=?

Solution: When such type of problems are given we have to follow one method as shown below.

Fraction for % is

7*7=49 14-15=1 is difference between C.I and S.I

1———>40

49———>?   =Principle

15———>?   = C.I

14———>? = S.I

Problem 2: P=?, R=15%,T=2 years,C.I-S.I=180

Solution:

Fraction for 15% is

20*20=400 129-120=9

9———>180

400——->?

is principal

## Compound Interest Part 4

Problem 1: P=?, R=%, T=2 years, 2nd year C.I=9.10

Solution:

Fraction for % is 2nd year C.I=12+1=13

13———>9.10

144——–>?

is principle.

Problem 2: P=?, R=%, T=2years, 2nd year C.I=8

Solution:

Fraction for % is 2nd year C.I 15+1=16

16——->8

225—–>?

is principle

## Compound Interest Part 5

Problem 1: P=?, R=20%, T=1 year 73 days, C.I=1240

Solution:

Fraction for 20%= 5+1.2 =6.2 is C.I

6.2———–>1240

25————->?

is principle.

Problem 2: P=?,R=%, T=1 year 4 months, C.I=1782

Solution:

Fraction for % is 8+1=9

8+3=11

11———->1782

64————>?

is principal.