B) Suppose that regular raises at your job allow you to increase your annual payment by 5% each year. For simplicity, assume this is a nominal rate, and your payment amount increases continuously. How long will it take to pay off the mortgage

Respuesta :

Answer:

Time period required to pay off the mortgage = 18 years            

Explanation:

Note: This question is incomplete and lacks necessary data to solve. But I have found that necessary data on the internet, which I have written down and solved the question accordingly.

Data Missing:

Buying Cost of House = $320000

Interest rate = 7%

Annual Mortgage Payment = $25525.8

Now, we are required to calculate the time period required to pay off the mortgage.

Solution:

Data Given:

Increase in annual payment percentage = 5%

So,

Formula:

P = C[tex]e^{A-i}[/tex] +  C[tex]e^{2(A-i)}[/tex] +   C[tex]e^{3(A-i)}[/tex]  + ........ + C[tex]e^{n(A-i)}[/tex]

Where,

P = Buying Cost of House = $320000

i = interest rate = 7% = 0.07

A = Increase in annual payment percentage = 5% = 0.05

C = Annual Mortgage Payment = $25525.8

P = C[tex]e^{A-i}[/tex] +  C[tex]e^{2(A-i)}[/tex] +   C[tex]e^{3(A-i)}[/tex]  + ........ + C[tex]e^{n(A-i)}[/tex]

In this formula, we have all the required things expect the value of n, which we have to calculate.

n = Time period required to pay the mortgage.

So,

$320000 = 25525.8 [tex]e^{0.05 - 0.07}[/tex] + 25525.8 [tex]e^{2(0.05 - 0.07)}[/tex] + 25525.8 [tex]e^{3(0.05 - 0.07)}[/tex] + ..... + 25525.8 [tex]e^{n(0.05 - 0.07)}[/tex]

Taking 25525.8 common,

320000 = 25525.8  ( [tex]e^{-0.02}[/tex] +  [tex]e^{-0.04}[/tex]  + [tex]e^{-0.06}[/tex] + .... + [tex]e^{-0.02n}[/tex] )

320000/25525.8  = ( [tex]e^{-0.02}[/tex] +  [tex]e^{-0.04}[/tex]  + [tex]e^{-0.06}[/tex] + .... + [tex]e^{-0.02n}[/tex] )

12.536 = ( [tex]e^{-0.02}[/tex] +  [tex]e^{-0.04}[/tex]  + [tex]e^{-0.06}[/tex] + .... + [tex]e^{-0.02n}[/tex] )

Taking e common:

12.536 = [tex]e^{-0.02 -0.04 - 0.06 + .... -0.02n}[/tex]

Taking Ln to solve for n, we get:

n = 17.89

n ≈ 18

n = 18 years

Hence, Time period required to pay off the mortgage = 18 years