1. **State the problem:** Walter wants to invest a sum of money now so that it grows to 200000 by the time his son is 21 years old. The son is currently 12, so the investment period is $21 - 12 = 9$ years. 2. **Formula used:** For compound interest, the future value $A$ is given by: $$A = P \left(1 + \frac{r}{n}\right)^{nt}$$ where: - $P$ is the principal (initial deposit), - $r$ is the annual interest rate (decimal), - $n$ is the number of compounding periods per year, - $t$ is the time in years. 3. **Given values:** - $A = 200000$ - $r = 0.12$ (12%) - $n = 6$ (bimonthly means every 2 months, so 6 times a year) - $t = 9$ 4. **Find $P$:** Rearranging the formula to solve for $P$: $$P = \frac{A}{\left(1 + \frac{r}{n}\right)^{nt}}$$ 5. **Calculate:** $$P = \frac{200000}{\left(1 + \frac{0.12}{6}\right)^{6 \times 9}} = \frac{200000}{\left(1 + 0.02\right)^{54}} = \frac{200000}{(1.02)^{54}}$$ 6. Calculate $(1.02)^{54}$: $$ (1.02)^{54} \approx 2.9387 $$ 7. Finally, $$P = \frac{200000}{2.9387} \approx 68056.64$$ **Answer:** Walter must deposit approximately **68056.64** now to have 200000 in 9 years with 12% interest compounded bimonthly.