Compound Interest 30Ed8E
1. **State the problem:**
Evaluate the expression $$P\left(1 + \frac{r}{k}\right)^{kn}$$ given $$P=4000$$, $$r=0.08$$ (8%), $$k=4$$, and $$n=20$$.
2. **Formula and explanation:**
This formula is used to calculate compound interest where:
- $$P$$ is the principal amount,
- $$r$$ is the annual interest rate (in decimal),
- $$k$$ is the number of compounding periods per year,
- $$n$$ is the number of years.
The term $$\left(1 + \frac{r}{k}\right)^{kn}$$ represents the growth factor after $$n$$ years.
3. **Substitute the values:**
$$P = 4000$$
$$r = 0.08$$
$$k = 4$$
$$n = 20$$
Calculate the inside of the parentheses:
$$1 + \frac{r}{k} = 1 + \frac{0.08}{4} = 1 + 0.02 = 1.02$$
Calculate the exponent:
$$kn = 4 \times 20 = 80$$
4. **Calculate the expression:**
$$4000 \times (1.02)^{80}$$
5. **Evaluate $$ (1.02)^{80} $$:**
Using a calculator:
$$ (1.02)^{80} \approx 4.922$$
6. **Multiply by $$P$$:**
$$4000 \times 4.922 = 19688$$
7. **Final answer rounded to two decimal places:**
$$19688.00$$
**Answer:**
$$\boxed{19688.00}$$