9. (6 points) A train takes 17 seconds to completely pass a 650-meter-long bridge, the train is 200 meters long, and the speed of the train is 50 meters per second.
【Solution】Solution: $(650+200) \div 17$,
$$
\begin{array}{l}
=850 \div 17, \\
=50 \text { (m/s), }
\end{array}
$$

Answer: The speed of the train is 50 meters per second; therefore, the answer is: 50.