13. (15 points) If 3 CNC machines can process 960 of the same parts in 4 hours, how long will it take for 1 CNC machine to process 400 of the same parts?
【Analysis】First, find out how many parts 1 CNC machine can process in 4 hours, then find out how many parts 1 CNC machine can process in 1 hour, and finally, we can find out how long it takes for 1 CNC machine to process 400 identical parts.

【Solution】Solution: $400 \div(960 \div 3 \div 4)$,
$$
\begin{array}{l}
=400 \div(320 \div 4), \\
=400 \div 80, \\
=5 \text { (hours); }
\end{array}
$$

Answer: It takes 5 hours for 1 CNC machine to process 400 identical parts.