2.3 continuous compound interests

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Continuous Compound Interest

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Page 1: 2.3 continuous compound interests

Continuous Compound Interest

Page 2: 2.3 continuous compound interests

We have the PINA formula for the return of periodic compound interest from the last section.

Continuous Compound Interest

Page 3: 2.3 continuous compound interests

P = principal,i = periodic rate, N = total number of periods A = accumulated valuethen P(1 + i )N = A

We have the PINA formula for the return of periodic compound interest from the last section. Let

Continuous Compound Interest

Page 4: 2.3 continuous compound interests

Example A. We deposited $1000 in an account with annual compound interest rater = 8%, compounded 4 times a year. How much will be there after 20 years?

We have the PINA formula for the return of periodic compound interest from the last section. Let

Continuous Compound Interest

P = principal,i = periodic rate, N = total number of periods A = accumulated valuethen P(1 + i )N = A

Page 5: 2.3 continuous compound interests

Example A. We deposited $1000 in an account with annual compound interest rater = 8%, compounded 4 times a year. How much will be there after 20 years?

P = 1000, yearly rate is 0.08,

We have the PINA formula for the return of periodic compound interest from the last section. Let

Continuous Compound Interest

P = principal,i = periodic rate, N = total number of periods A = accumulated valuethen P(1 + i )N = A

Page 6: 2.3 continuous compound interests

Example A. We deposited $1000 in an account with annual compound interest rater = 8%, compounded 4 times a year. How much will be there after 20 years?

40.08

P = 1000, yearly rate is 0.08, so i = = 0.02,

We have the PINA formula for the return of periodic compound interest from the last section. Let

Continuous Compound Interest

P = principal,i = periodic rate, N = total number of periods A = accumulated valuethen P(1 + i )N = A

Page 7: 2.3 continuous compound interests

Example A. We deposited $1000 in an account with annual compound interest rater = 8%, compounded 4 times a year. How much will be there after 20 years?

40.08

P = 1000, yearly rate is 0.08, so i = = 0.02, in 20 years,N = (20 years)(4 times per years) = 80 periods

We have the PINA formula for the return of periodic compound interest from the last section. Let

Continuous Compound Interest

P = principal,i = periodic rate, N = total number of periods A = accumulated valuethen P(1 + i )N = A

Page 8: 2.3 continuous compound interests

Example A. We deposited $1000 in an account with annual compound interest rater = 8%, compounded 4 times a year. How much will be there after 20 years?

40.08

P = 1000, yearly rate is 0.08, so i = = 0.02, in 20 years,N = (20 years)(4 times per years) = 80 periods Hence A = 1000(1 + 0.02 )80 4875.44 $

We have the PINA formula for the return of periodic compound interest from the last section. Let

Continuous Compound Interest

P = principal,i = periodic rate, N = total number of periods A = accumulated valuethen P(1 + i )N = A

Page 9: 2.3 continuous compound interests

Example A. We deposited $1000 in an account with annual compound interest rater = 8%, compounded 4 times a year. How much will be there after 20 years?

40.08

P = 1000, yearly rate is 0.08, so i = = 0.02, in 20 years,N = (20 years)(4 times per years) = 80 periods Hence A = 1000(1 + 0.02 )80 4875.44 $

We have the PINA formula for the return of periodic compound interest from the last section. Let

What happen if we keep everything the same but compound more often, that is, increase K, the number of periods?

Continuous Compound Interest

P = principal,i = periodic rate, N = total number of periods A = accumulated valuethen P(1 + i )N = A

Page 10: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

Continuous Compound Interest

Page 11: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

Continuous Compound Interest

Page 12: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

Continuous Compound Interest

Page 13: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000

Continuous Compound Interest

Page 14: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000

Continuous Compound Interest

Page 15: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

Continuous Compound Interest

Page 16: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

Continuous Compound Interest

Page 17: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

N = (20 years)(1000 times per years) = 20000

Continuous Compound Interest

Page 18: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

N = (20 years)(1000 times per years) = 20000Hence A = 1000(1 + 0.00008 )20000

Continuous Compound Interest

Page 19: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

N = (20 years)(1000 times per years) = 20000Hence A = 1000(1 + 0.00008 )20000 4952.72 $

Continuous Compound Interest

Page 20: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

N = (20 years)(1000 times per years) = 20000Hence A = 1000(1 + 0.00008 )20000 4952.72 $

For 10000 times a year, 100000.08 i = = 0.000008,

Continuous Compound Interest

Page 21: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

N = (20 years)(1000 times per years) = 20000Hence A = 1000(1 + 0.00008 )20000 4952.72 $

For 10000 times a year, 100000.08 i = = 0.000008,

N = (20 years)(10000 times per years) = 200000

Continuous Compound Interest

Page 22: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

N = (20 years)(1000 times per years) = 20000Hence A = 1000(1 + 0.00008 )20000 4952.72 $

For 10000 times a year, 100000.08 i = = 0.000008,

N = (20 years)(10000 times per years) = 200000Hence A = 1000(1 + 0.000008 )200000

Continuous Compound Interest

Page 23: 2.3 continuous compound interests

Example B. We deposited $1000 in an account with annual compound interest rater = 8%. How much will be there after 20 years if it's compounded 100 times a year? 1000 times a year? 10000 times a year?

P = 1000, r = 0.08, T = 20,

For 100 times a year, 1000.08 i = = 0.0008,

N = (20 years)(100 times per years) = 2000Hence A = 1000(1 + 0.0008 )2000 4949.87 $

For 1000 times a year, 10000.08 i = = 0.00008,

N = (20 years)(1000 times per years) = 20000Hence A = 1000(1 + 0.00008 )20000 4952.72 $

For 10000 times a year, 100000.08 i = = 0.000008,

N = (20 years)(10000 times per years) = 200000Hence A = 1000(1 + 0.000008 )200000 4953.00 $

Continuous Compound Interest

Page 24: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

Continuous Compound Interest

Page 25: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

4 times a year 4875.44 $

Continuous Compound Interest

Page 26: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

100 times a year 4949.87 $ 4 times a year 4875.44 $

Continuous Compound Interest

Page 27: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

10000 times a year 4953.00 $

1000 times a year 4952.72 $

100 times a year 4949.87 $ 4 times a year 4875.44 $

Continuous Compound Interest

Page 28: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

10000 times a year 4953.00 $

1000 times a year 4952.72 $

100 times a year 4949.87 $ 4 times a year 4875.44 $

Continuous Compound Interest

Page 29: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

10000 times a year 4953.00 $

1000 times a year 4952.72 $

100 times a year 4949.87 $ 4 times a year 4875.44 $

Continuous Compound Interest

Page 30: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

10000 times a year 4953.00 $

1000 times a year 4952.72 $

100 times a year 4949.87 $ 4 times a year 4875.44 $

4953.03 $

Continuous Compound Interest

Page 31: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

10000 times a year 4953.00 $

1000 times a year 4952.72 $

100 times a year 4949.87 $ 4 times a year 4875.44 $

4953.03 $

We call this amount the continuously compounded return.

Continuous Compound Interest

Page 32: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

10000 times a year 4953.00 $

1000 times a year 4952.72 $

100 times a year 4949.87 $ 4 times a year 4875.44 $

4953.03 $

We call this amount the continuously compounded return.This way of compounding is called compounded continuously.

Continuous Compound Interest

Page 33: 2.3 continuous compound interests

We list the results below as the number compounded per yearK gets larger and larger.

10000 times a year 4953.00 $

1000 times a year 4952.72 $

100 times a year 4949.87 $ 4 times a year 4875.44 $

4953.03 $

We call this amount the continuously compounded return.This way of compounding is called compounded continuously.The reason we want to compute interest this way is becausethe formula for computing continously compound return is easy to manipulate mathematically.

Continuous Compound Interest

Page 34: 2.3 continuous compound interests

The Perta-Formula for Continuously Compounded ReturnContinuous Compound Interest

Page 35: 2.3 continuous compound interests

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

Continuous Compound Interest

Page 36: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years?

b. If r = 12%, how much will be there after 20 years?

c. If r = 16%, how much will be there after 20 years?

Continuous Compound Interest

Page 37: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years? P = 1000, r = 0.08, t = 20.

b. If r = 12%, how much will be there after 20 years?

c. If r = 16%, how much will be there after 20 years?

Continuous Compound Interest

Page 38: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years? P = 1000, r = 0.08, t = 20. So the continuously compounded return is A = 1000*e0.08*20

b. If r = 12%, how much will be there after 20 years?

c. If r = 16%, how much will be there after 20 years?

Continuous Compound Interest

Page 39: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years? P = 1000, r = 0.08, t = 20. So the continuously compounded return is A = 1000*e0.08*20 = 1000*e1.6 4953.03$

b. If r = 12%, how much will be there after 20 years?

c. If r = 16%, how much will be there after 20 years?

Continuous Compound Interest

Page 40: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years? P = 1000, r = 0.08, t = 20. So the continuously compounded return is A = 1000*e0.08*20 = 1000*e1.6 4953.03$

b. If r = 12%, how much will be there after 20 years?r = 12%, A = 1000*e0.12*20

c. If r = 16%, how much will be there after 20 years?

Continuous Compound Interest

Page 41: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years? P = 1000, r = 0.08, t = 20. So the continuously compounded return is A = 1000*e0.08*20 = 1000*e1.6 4953.03$

b. If r = 12%, how much will be there after 20 years?r = 12%, A = 1000*e0.12*20 = 1000e 2.4 11023.18$

c. If r = 16%, how much will be there after 20 years?

Continuous Compound Interest

Page 42: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years? P = 1000, r = 0.08, t = 20. So the continuously compounded return is A = 1000*e0.08*20 = 1000*e1.6 4953.03$

b. If r = 12%, how much will be there after 20 years?r = 12%, A = 1000*e0.12*20 = 1000e 2.4 11023.18$

c. If r = 16%, how much will be there after 20 years?r = 16%, A = 1000*e0.16*20

Continuous Compound Interest

Page 43: 2.3 continuous compound interests

Example C. a. We deposited $1000 in an account compounded continuously.

The Perta-Formula for Continuously Compounded ReturnLet P = principal r = annual interest rate (compound continuously) t = number of year A = accumulated value, then Per*t = A where e 2.71828..

a. if r = 8%, how much will be there after 20 years? P = 1000, r = 0.08, t = 20. So the continuously compounded return is A = 1000*e0.08*20 = 1000*e1.6 4953.03$

b. If r = 12%, how much will be there after 20 years?r = 12%, A = 1000*e0.12*20 = 1000e 2.4 11023.18$

c. If r = 16%, how much will be there after 20 years?r = 16%, A = 1000*e0.16*20 = 1000*e 3.2 24532.53$

Continuous Compound Interest

Page 44: 2.3 continuous compound interests

Continuous Compound InterestAbout the Number e

Page 45: 2.3 continuous compound interests

Just as the number π, the number e 2.71828… occupies a special place in mathematics.

Continuous Compound InterestAbout the Number e

Page 46: 2.3 continuous compound interests

Just as the number π, the number e 2.71828… occupies a special place in mathematics. Where as π 3.14156… is a geometric constant–the ratio of the circumference to the diameter of a circle, e is derived from calculations.

Continuous Compound InterestAbout the Number e

Page 47: 2.3 continuous compound interests

Just as the number π, the number e 2.71828… occupies a special place in mathematics. Where as π 3.14156… is a geometric constant–the ratio of the circumference to the diameter of a circle, e is derived from calculations. For example, the following sequence of numbers zoom–in on the number,

( )1,2 1 … ( )4,

5 4

( )3,4 3

( )2,3 2 2.71828…

Continuous Compound InterestAbout the Number e

Page 48: 2.3 continuous compound interests

Just as the number π, the number e 2.71828… occupies a special place in mathematics. Where as π 3.14156… is a geometric constant–the ratio of the circumference to the diameter of a circle, e is derived from calculations. For example, the following sequence of numbers zoom–in on the number,

( 2.71828…)the same as

( )1,2 1 … ( )4,

5 4

( )3,4 3

( )2,3 2 2.71828…which is

Continuous Compound InterestAbout the Number e

Page 49: 2.3 continuous compound interests

Just as the number π, the number e 2.71828… occupies a special place in mathematics. Where as π 3.14156… is a geometric constant–the ratio of the circumference to the diameter of a circle, e is derived from calculations. For example, the following sequence of numbers zoom–in on the number,

( 2.71828…)the same as

( )1,2 1 … ( )4,

5 4

( )3,4 3

( )2,3 2 2.71828…which is

Continuous Compound InterestAbout the Number e

Page 50: 2.3 continuous compound interests

Just as the number π, the number e 2.71828… occupies a special place in mathematics. Where as π 3.14156… is a geometric constant–the ratio of the circumference to the diameter of a circle, e is derived from calculations. For example, the following sequence of numbers zoom–in on the number,

This number emerges often in the calculation of problems in physical science, natural science, finance and in mathematics.

( 2.71828…)the same as

( )1,2 1 … ( )4,

5 4

( )3,4 3

( )2,3 2 2.71828…which is

Continuous Compound InterestAbout the Number e

Page 51: 2.3 continuous compound interests

Just as the number π, the number e 2.71828… occupies a special place in mathematics. Where as π 3.14156… is a geometric constant–the ratio of the circumference to the diameter of a circle, e is derived from calculations. For example, the following sequence of numbers zoom–in on the number,

http://en.wikipedia.org/wiki/E_%28mathematical_constant%29

This number emerges often in the calculation of problems in physical science, natural science, finance and in mathematics. Because of its importance, the irrational number 2.71828… is named as “e” and it’s called the “natural” base number.

( 2.71828…)the same as

http://www.ndt-ed.org/EducationResources/Math/Math-e.htm

( )1,2 1 … ( )4,

5 4

( )3,4 3

( )2,3 2 2.71828…which is

Continuous Compound InterestAbout the Number e