Loan Payment
1. **State the problem:**
You take a loan of 120000 with an annual interest rate of 4.7% compounded monthly for 20 years.
(a) Find the monthly loan payment.
(b) Find the total interest paid.
2. **Identify the formula for monthly payment:**
The formula for monthly payment $M$ on a loan principal $P$ with monthly interest rate $r$ over $n$ months is:
$$M = P \frac{r(1+r)^n}{(1+r)^n - 1}$$
3. **Calculate monthly interest rate $r$ and number of payments $n$:**
Annual interest rate = 4.7%, so monthly interest rate:
$$r = \frac{4.7}{100} \times \frac{1}{12} = 0.0039167$$
Number of months in 20 years:
$$n = 20 \times 12 = 240$$
4. **Calculate monthly payment $M$:**
Plug in values:
$$M = 120000 \times \frac{0.0039167 (1 + 0.0039167)^{240}}{(1 + 0.0039167)^{240} - 1}$$
Calculate $(1+r)^n$:
$$ (1 + 0.0039167)^{240} \approx 2.5820 $$
Then:
$$M = 120000 \times \frac{0.0039167 \times 2.5820}{2.5820 - 1} = 120000 \times \frac{0.010108}{1.5820} = 120000 \times 0.006389 = 766.68$$
So monthly payment is approximately **766.68**.
5. **Calculate total interest paid:**
Total payment over 240 months:
$$240 \times 766.68 = 184003.20$$
Total interest paid:
$$184003.20 - 120000 = 64003.20$$
**Final answers:**
- (a) Monthly payment = $766.68$
- (b) Total interest paid = $64003.20$