1. **State the problem:** Robert wants to save 50000 in 5 years with an annual interest rate of 4% compounded monthly. We need to find the present value (initial investment) he should invest today.
2. **Formula used:** For compound interest compounded monthly, the future value $A$ is given by:
$$A = P \left(1 + \frac{r}{n}\right)^{nt}$$
where:
- $P$ is the principal (initial investment),
- $r$ is the annual interest rate (decimal),
- $n$ is the number of compounding periods per year,
- $t$ is the number of years.
3. **Given values:**
- $A = 50000$
- $r = 0.04$
- $n = 12$
- $t = 5$
4. **Rearrange formula to solve for $P$:**
$$P = \frac{A}{\left(1 + \frac{r}{n}\right)^{nt}}$$
5. **Substitute values:**
$$P = \frac{50000}{\left(1 + \frac{0.04}{12}\right)^{12 \times 5}}$$
6. **Calculate inside the parentheses:**
$$1 + \frac{0.04}{12} = 1 + 0.0033333 = 1.0033333$$
7. **Calculate the exponent:**
$$12 \times 5 = 60$$
8. **Calculate the power:**
$$1.0033333^{60} \approx 1.221392$$
9. **Calculate $P$:**
$$P = \frac{50000}{1.221392}$$
10. **Simplify:**
$$P \approx 40918.68$$
**Answer:** Robert should invest approximately **40918.68** today to reach his goal of 50000 in 5 years with 4% annual interest compounded monthly.
Investment Principal C3B5A3
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