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Sharp CS-2870 User Manual

Page 25

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COMPOUND INTEREST
Calculate the new balance on a deposit which is compounded quarterly for 4 years at

a given annual interest rate.

SOLUTION:

1. Calculate the quarterly interest rate.

2. Calculate the new balance (principal plus interest)

FORMULA:

New balance = P (1 + i)"

Where

P = amount of deposit (principal)

i

= interest rate per period

n = number of years x 4

If

P = $6,150

i

= 5% annum -s- 4 periods = 0.0125

n = 4 years x 4 periods = 16

Then 6,150 (1 + 0.0125)^® = $7,502.32 (New Balance)

EXAMPLE:

(1)

(2)

(3)

(4)

.05 0

0.05

0 05 ^

4 a

4' =

0.0125

0 0125 *

a

0.0125

00125 +

1 a

1.0125

1- +

s

1-0125 0

1.0125

1-0125

X

[i]

1-0125 ^

1.02515625

1-02515625 *

0

1.02515625

1-02515625

X

m

1-02515625 =

1.05094533691

1-05094533691 *

E

1.05094533691

1-05094533691 x

E

1-05094533691 =

1.10448610117

1-10448610117 =♦=

E

1.10448610117

1-10448610117

X

E

1-10448610117 =

1.21988954767

1-21988954767 >1'

E

1.21988954767

1-21988954767 x

6150 [±]

6.150- =

7,502.32071817

7.502-32071817 *■

— F

6

— 5

— 4

3

2

— 1

0

Annual int. rate

Quarterly int. rate

(1 +i)

(1+i)^

(1 + i)^

(1 +i)B

(1 +i)’

Principal

New balance

23