To find out how much the car will be worth after 7 years, we can use the given depreciation formula:
\[ v(t) = 40000(0.89)^t \]
We need to substitute \(t = 7\) into the equation:
\[ v(7) = 40000(0.89)^7 \]
Now, calculating \(0.89^7\):
\[ 0.89^7 \approx 0.5132 \]
Now, we can calculate \(v(7)\):
\[ v(7) \approx 40000 \times 0.5132 \approx 20528 \]
Thus, after 7 years, the car will be worth approximately $20,528.
So, an appropriate range for the car's worth after 7 years would be around $20,000 to $21,500.