Question: A computer chip designer purchased a car for $54,276.47, which included sales tax and registration. If the designer obtains a 5-year loan for the total amount at an annual interest rate of 4.5% compounded monthly, find the monthly car payment.
1. **State the problem:**
We need to find the monthly payment for a car loan of $54,276.47 over 5 years with an annual interest rate of 4.5% compounded monthly.
2. **Formula used:**
The monthly payment $M$ for a loan amount $P$ with monthly interest rate $r$ over $n$ months is given by the amortization formula:
$$
M = P \times \frac{r(1+r)^n}{(1+r)^n - 1}
$$
3. **Identify variables:**
- Principal $P = 54276.47$
- Annual interest rate = 4.5% = 0.045
- Monthly interest rate $r = \frac{0.045}{12} = 0.00375$
- Loan term = 5 years = $5 \times 12 = 60$ months
4. **Calculate $(1+r)^n$:**
$$
(1 + 0.00375)^{60} = 1.00375^{60}
$$
Using a calculator:
$$
1.00375^{60} \approx 1.2434
$$
5. **Calculate numerator:**
$$
r(1+r)^n = 0.00375 \times 1.2434 = 0.00466275
$$
6. **Calculate denominator:**
$$
(1+r)^n - 1 = 1.2434 - 1 = 0.2434
$$
7. **Calculate monthly payment $M$:**
$$
M = 54276.47 \times \frac{0.00466275}{0.2434}
$$
Simplify the fraction:
$$
\frac{0.00466275}{0.2434} \approx 0.01916
$$
So,
$$
M = 54276.47 \times 0.01916 \approx 1039.88
$$
**Final answer:**
The monthly car payment is approximately **$1039.88**.