1. **State the problem:** We have a loan of 9500 to be repaid with monthly payments of 325 at the beginning of each month. The interest rate is 9.50% compounded monthly. We need to find:
a) The number of payments required to repay the debt, rounding up to the next whole payment.
b) The size of the final payment, rounded to the nearest cent.
2. **Formula and important rules:** Since payments are at the beginning of each period, this is an annuity due. The present value $PV$ of an annuity due is given by:
$$PV = P \times \frac{1 - (1 + i)^{-n}}{i} \times (1 + i)$$
where:
- $P$ is the payment amount per period,
- $i$ is the monthly interest rate (annual rate divided by 12),
- $n$ is the number of payments.
We know $PV = 9500$, $P = 325$, and $i = \frac{9.5}{100 \times 12} = 0.0079167$ approximately.
3. **Find the number of payments $n$:**
Rearranging the formula:
$$\frac{PV}{P(1+i)} = \frac{1 - (1+i)^{-n}}{i}$$
Multiply both sides by $i$:
$$i \times \frac{PV}{P(1+i)} = 1 - (1+i)^{-n}$$
Then:
$$(1+i)^{-n} = 1 - i \times \frac{PV}{P(1+i)}$$
Take natural logarithm:
$$-n \ln(1+i) = \ln\left(1 - i \times \frac{PV}{P(1+i)}\right)$$
Solve for $n$:
$$n = - \frac{\ln\left(1 - i \times \frac{PV}{P(1+i)}\right)}{\ln(1+i)}$$
4. **Calculate intermediate values:**
$$i = \frac{9.5}{100 \times 12} = 0.0079167$$
$$1+i = 1.0079167$$
$$\frac{PV}{P(1+i)} = \frac{9500}{325 \times 1.0079167} = \frac{9500}{327.5729} \approx 28.99$$
$$i \times \frac{PV}{P(1+i)} = 0.0079167 \times 28.99 \approx 0.2294$$
$$1 - 0.2294 = 0.7706$$
$$\ln(0.7706) = -0.2607$$
$$\ln(1+i) = \ln(1.0079167) = 0.007885$$
5. **Calculate $n$:**
$$n = - \frac{-0.2607}{0.007885} = 33.06$$
Rounding up, the number of payments required is **34**.
6. **Calculate the size of the final payment:**
The total amount paid after 33 full payments is:
$$A = P \times \frac{(1+i)^n - 1}{i} \times (1+i)^{-1}$$
But since payments are at the beginning, the balance after 33 payments is:
$$B = PV \times (1+i)^{33} - P \times \frac{(1+i)^{33} - 1}{i}$$
Calculate $B$ to find the remaining balance before the 34th payment.
Calculate:
$$(1+i)^{33} = 1.0079167^{33} = e^{33 \times 0.007885} = e^{0.2602} = 1.2977$$
$$PV \times (1+i)^{33} = 9500 \times 1.2977 = 12328.15$$
$$\frac{(1+i)^{33} - 1}{i} = \frac{1.2977 - 1}{0.0079167} = \frac{0.2977}{0.0079167} = 37.60$$
$$P \times \frac{(1+i)^{33} - 1}{i} = 325 \times 37.60 = 12220$$
$$B = 12328.15 - 12220 = 108.15$$
So the final payment is approximately **108.15**.
**Final answers:**
- Number of payments required: **34**
- Size of the final payment: **108.15**
Loan Repayment 0610Fc
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