Question: Use the appropriate formula to find the value of the annuity.
b. Find the interest.
Periodic Deposit
Rate
Time
$2000 at the end of each year
5 % compounded annually
20 years
1. **State the problem:**
We want to find the future value of an annuity where $2000$ is deposited at the end of each year for $20$ years at an interest rate of $5\%$ compounded annually.
2. **Formula for the future value of an ordinary annuity:**
$$FV = P \times \frac{(1 + r)^n - 1}{r}$$
where:
- $P$ is the periodic deposit ($2000$),
- $r$ is the interest rate per period ($0.05$),
- $n$ is the number of periods ($20$).
3. **Calculate the future value:**
$$FV = 2000 \times \frac{(1 + 0.05)^{20} - 1}{0.05}$$
4. Calculate $(1 + 0.05)^{20}$:
$$1.05^{20} = 2.653297705$$
5. Substitute back:
$$FV = 2000 \times \frac{2.653297705 - 1}{0.05} = 2000 \times \frac{1.653297705}{0.05}$$
6. Simplify the fraction:
$$\frac{1.653297705}{0.05} = 33.0659541$$
7. Multiply by $2000$:
$$FV = 2000 \times 33.0659541 = 66131.9082$$
8. **Find the total amount deposited:**
$$\text{Total deposits} = 2000 \times 20 = 40000$$
9. **Calculate the interest earned:**
$$\text{Interest} = FV - \text{Total deposits} = 66131.9082 - 40000 = 26131.9082$$
**Final answers:**
- Future value of the annuity: $$66131.91$$
- Interest earned: $$26131.91$$