Annuity Balance Interest
1. **State the problem:** Janet saves 500 at the beginning of every month for 15 years in a fund with an annual interest rate of 4.75% compounded annually. We need to find:
a. The balance in the fund at the end of 15 years.
b. The total interest earned over the period.
2. **Identify the type of problem:** This is an annuity problem with monthly payments but interest compounded annually.
3. **Convert the problem to annual terms:** Since interest compounds annually, we consider the total amount saved each year.
Monthly saving = 500
Annual saving = 500 \times 12 = 6000
4. **Use the future value of an ordinary annuity formula:**
$$FV = P \times \frac{(1 + r)^n - 1}{r}$$
where
$P = 6000$ (annual payment),
$r = 0.0475$ (annual interest rate),
$n = 15$ (number of years).
5. **Calculate the future value:**
$$FV = 6000 \times \frac{(1 + 0.0475)^{15} - 1}{0.0475}$$
Calculate $(1 + 0.0475)^{15}$:
$$1.0475^{15} \approx 2.0004$$
Then,
$$FV = 6000 \times \frac{2.0004 - 1}{0.0475} = 6000 \times \frac{1.0004}{0.0475} \approx 6000 \times 21.06 = 126360$$
6. **Calculate total amount saved without interest:**
$$\text{Total principal} = 6000 \times 15 = 90000$$
7. **Calculate interest earned:**
$$\text{Interest} = FV - \text{Total principal} = 126360 - 90000 = 36360$$
8. **Round to nearest cent:**
a. Balance = 126360.00
b. Interest earned = 36360.00
**Final answers:**
- a. The balance in the fund at the end of 15 years is **126360.00**.
- b. The interest earned over the period is **36360.00**.