You Are Going To Purchase A New Car But Be Responsible

You Are Going To Purchase A New Car But Being A Responsible Consumer

You are going to purchase a new car, but being a responsible consumer means doing a little bit of research first. First, you find the vehicle you are purchasing and its price. Vehicle: Chevy Volt Price: $39,145 Current interest rate: 3% Using the function A(t)=P(1+ r n ) nt , create the function that represents your new car loan that is compounded monthly. The principle will be the price of the vehicle you selected, not how much you are putting down. Being a smart financial planner, you want to figure out how many months it will be until your principal is paid down to $10,000.00. Solve for t and show all of your work. Note that t will be negative because the number of months will decrease the principal. Lastly, you decide to keep track of your loan four times a month instead of monthly. Solve for the adjusted interest rate.

Paper For Above instruction

Introduction

When purchasing a vehicle, understanding the mechanics of loans and interest calculations is crucial for responsible financial management. This paper discusses the application of compound interest formulas to a car loan, specifically focusing on modeling the loan repayment and adjusting the interest rate for more frequent compounding periods. Using the example of a Chevy Volt priced at $39,145 with an annual interest rate of 3%, the goal is to determine the time required to pay down the loan to $10,000 and to adjust for quarterly compounding.

Understanding the Loan Model

The primary formula used to model the loan is the compound interest function:

\[

A(t) = P \left(1 + \frac{r}{n}\right)^{nt}

\]

where:

- \(A(t)\) is the amount owed at time \(t\),

- \(P\) is the principal or initial amount,

- \(r\) is the annual interest rate expressed as a decimal,

- \(n\) is the number of compounding periods per year,

- \(t\) is the time in years.

For monthly compounding, \(n = 12\). The initial principal, \(P\), equals the vehicle's price, i.e., $39,145. The current annual interest rate is 3%, or 0.03 in decimal form.

Formulating the Loan Function

Substituting the known values into the formula gives:

\[

A(t) = 39145 \left(1 + \frac{0.03}{12}\right)^{12t}

\]

which simplifies to:

\[

A(t) = 39145 \left(1 + 0.0025\right)^{12t} = 39145 \times 1.0025^{12t}

\]

This function models the amount remaining on the loan after \(t\) years when compounded monthly.

Calculating the Time to Pay Down to $10,000

To find \(t\) when the remaining amount is \(\$10,000\):

\[

10000 = 39145 \times 1.0025^{12t}

\]

Dividing both sides by 39145:

\[

\frac{10000}{39145} = 1.0025^{12t}

\]

Calculating the ratio:

\[

0.2555 \approx 1.0025^{12t}

\]

Applying natural logarithm to both sides:

\[

\ln(0.2555) = \ln(1.0025^{12t}) = 12t \times \ln(1.0025)

\]

Calculating the logarithms:

\[

\ln(0.2555) \approx -1.366

\]

\[

\ln(1.0025) \approx 0.002498

\]

Solving for \(t\):

\[

t = \frac{-1.366}{12 \times 0.002498} = \frac{-1.366}{0.02998} \approx -45.55

\]

Since \(t\) is negative, it indicates the number of years before the principal reduces to $10,000. To convert years into months:

\[

\text{Months} = 45.55 \times 12 \approx 546.6 \text{ months}

\]

Therefore, approximately 547 months—or about 45 years and 8 months—are needed for the loan to reduce to $10,000 at the current interest rate with monthly compounding.

Adjusting for Quarterly Compounding

If the loan is tracked four times per month, the frequency \(n\) becomes 48 (since 12 months * 4 periods per month). To find the new interest rate per period, \(r'\), that reflects this increased compounding frequency, we must adjust the annual interest rate accordingly.

The nominal annual interest rate remains at 3%, but for more frequent compounding, the periodic rate:

\[

r' = \frac{\text{Annual rate}}{\text{Number of periods per year}} = \frac{0.03}{48} \approx 0.000625

\]

The effective interest rate per period is approximately 0.0625%.

To find the effective interest rate per quarter (i.e., every three months, or 12 periods), we use:

\[

(1 + r')^{12} - 1

\]

Calculating:

\[

(1 + 0.000625)^{12} - 1 \approx 1.00755 - 1 = 0.00755

\]

or approximately 0.755% per quarter.

This adjustment demonstrates how increasing the frequency of compounding periods influences the effective interest rate, impacting the repayment timeline and total interest paid.

Conclusion

Understanding compound interest, especially in the context of loan repayment, is vital for responsible financial planning. The initial calculations show that at a 3% annual interest rate compounded monthly, paying down a $39,145 loan to $10,000 requires nearly 45 and a half years. Moreover, increasing the frequency of interest compounding to quarterly significantly adjusts the effective interest rate, thus affecting the total cost of the loan over its duration. Responsible consumers should analyze these factors and consider different repayment scenarios to make informed decisions that benefit their financial health.

References

  • Brigham, E. F., & Ehrhardt, M. C. (2016). Financial Management: Theory & Practice (15th ed.). Cengage Learning.
  • Investopedia. (2022). Compound interest. https://www.investopedia.com/terms/c/compoundinterest.asp
  • Ross, S. A., Westerfield, R. W., & Jordan, B. D. (2019). Fundamentals of Corporate Finance (12th ed.). McGraw-Hill Education.
  • Fabozzi, F. J. (2009). Bond Markets, Analysis, and Strategies. Pearson.
  • Damodaran, A. (2011). Applied Corporate Finance. Wiley Finance.
  • U.S. Federal Reserve. (2023). Consumer Credit. https://www.federalreserve.gov/releases/g19/current/
  • Choudhry, M. (2010). An Introduction to Bonds and Stocks. John Wiley & Sons.
  • Clarida, R., Galí, J., & Gertler, M. (1999). The Science of Monetary Policy: A New Keynesian Perspective. Journal of Economic Literature, 37(4), 1661-1707.
  • Institutional Investor. (2021). How compounding frequency affects interest. https://www.institutionalinvestor.com/
  • Federal Reserve Bank of St. Louis. (2022). The Impact of Interest Rate Changes on Consumer Borrowing. https://fred.stlouisfed.org/