1. **State the problem:** We need to find an equation that models the value $V$ of a Certificate of Deposit (CD) after $t$ years, given that $V=5500$ at $t=1$ and $V=7320.50$ at $t=4$. 2. **Identify the model:** CDs typically grow with compound interest, so we use the exponential growth model: $$V = V_0 \cdot r^{t}$$ where $V_0$ is the initial value, $r$ is the growth rate per year, and $t$ is the number of years. 3. **Use the given data:** We know $V(1) = 5500$, so: $$5500 = V_0 \cdot r^{1} = V_0 r$$ and $V(4) = 7320.50$, so: $$7320.50 = V_0 \cdot r^{4}$$ 4. **Express $V_0$ from the first equation:** $$V_0 = \frac{5500}{r}$$ 5. **Substitute $V_0$ into the second equation:** $$7320.50 = \frac{5500}{r} \cdot r^{4} = 5500 \cdot r^{3}$$ 6. **Solve for $r^{3}$:** $$r^{3} = \frac{7320.50}{5500} = 1.33$$ 7. **Take the cube root to find $r$:** $$r = \sqrt[3]{1.33} \approx 1.100$$ 8. **Find $V_0$ using $r$:** $$V_0 = \frac{5500}{1.100} = 5000$$ 9. **Write the final model:** $$\boxed{V = 5000 \cdot (1.1)^{t}}$$ This equation models the CD's value $V$ after $t$ years, starting from $5000$ at $t=0$ and growing at about 10% per year.