1. The problem asks to find the common ratio of the geometric sequence 8, -40, 200, ... 2. Recall that in a geometric sequence, the common ratio $r$ is found by dividing any term by the previous term: $$r = \frac{a_{n+1}}{a_n}$$ 3. Using the first two terms: $$r = \frac{-40}{8}$$ 4. Simplify the fraction: $$r = \frac{\cancel{-40}}{\cancel{8}} = -5$$ 5. To verify, check the ratio between the second and third terms: $$r = \frac{200}{-40} = -5$$ 6. Since both ratios are equal, the common ratio is confirmed as $-5$. **Final answer:** The common ratio is $-5$.