Answer:
3 min
Step-by-step explanation:
These are all independent actions.
If you put 1 cat in a room with 1 mouse, it will take 3 min to catch the mouse.
If you put 2 cats in a room with 2 mice, they will act independently and it will take 3 min for each one to catch a mouse.
If you put 3 cats in a room with 3 mice, they will act independently and it will take 3 min for each one to catch a mouse.
If you put 100 cats in a room with 100 mice, they will act independently and it will take 3 min for each one to catch a mouse.
Each cat will finish at the same time — 3 min.
