High School

Which of these expressions can be used to calculate the monthly payment for a 20-year loan for [tex]\$ 215,000[/tex] at [tex]5.4\%[/tex] interest, compounded monthly?

A. [tex]\frac{\$ 215,000 \cdot 0.0045(1-0.0045)^{240}}{(1-0.0045)^{240}-1}[/tex]

B. [tex]\frac{\$ 215,000 \cdot 0.0045(1+0.0045)^{240}}{(1+0.0045)^{240}-1}[/tex]

C. [tex]\frac{\$ 215,000 \cdot 0.0045(1-0.0045)^{240}}{(1-0.0045)^{240}+1}[/tex]

D. [tex]\frac{\$ 215,000 \cdot 0.0045(1+0.0045)^{240}}{1.0 \cdot 0.05155 \cdot 1240}[/tex]

Answer :

Sure, let's go through the steps to determine which expression can be used to calculate the monthly payment for a 20-year loan of \[tex]$215,000 with an interest rate of 5.4%, compounded monthly.

### Step-by-Step Solution:

1. Understand the Parameters:
- Principal (P) = \$[/tex]215,000
- Annual interest rate = 5.4%
- Monthly interest rate (r) = 5.4% / 12 = 0.45% = 0.0045
- Loan term = 20 years
- Number of monthly payments (n) = 20 years \* 12 months/year = 240

2. Monthly Payment Formula:
The formula to calculate the monthly payment for a loan is:
[tex]\[
M = P \cdot \frac{r(1+r)^n}{(1+r)^n - 1}
\][/tex]
where:
- [tex]\( M \)[/tex] is the monthly payment
- [tex]\( P \)[/tex] is the loan principal
- [tex]\( r \)[/tex] is the monthly interest rate
- [tex]\( n \)[/tex] is the number of payments

3. Substitute the Values into the Formula:
- [tex]\( P = 215000 \)[/tex]
- [tex]\( r = 0.0045 \)[/tex]
- [tex]\( n = 240 \)[/tex]

Our formula becomes:
[tex]\[
M = 215000 \cdot \frac{0.0045(1+0.0045)^{240}}{(1+0.0045)^{240} - 1}
\][/tex]

4. Compare with Given Options:
Let's match this formula with the given expressions:

- Option A: [tex]\(\frac{215000 \cdot 0.0045(1-0.0045)^{240}}{(1-0.0045)^{240}-1}\)[/tex]
- Option B: [tex]\(\frac{215000 \cdot 0.0045(1+0.0045)^{240}}{(1+0.0045)^{240}-1}\)[/tex]
- Option C: [tex]\(\frac{215000 \cdot 0.0045(1-0.0045)^{240}}{(1-0.0045)^{240}+1}\)[/tex]
- Option D: [tex]\(\frac{215000 \cdot 0.0045(1+0.0045)^{240}}{1.0 \cdot 0.05155(1240)}\)[/tex]

Option B is the correct match:
[tex]\[
\frac{215000 \cdot 0.0045(1+0.0045)^{240}}{(1+0.0045)^{240}-1}
\][/tex]

Therefore, the expression that can be used to calculate the monthly payment for a 20-year loan of \$215,000 at 5.4% interest, compounded monthly, is:
[tex]\[
\boxed{B}
\][/tex]