Mice in the House

[Joseph Smith]

Hi there!
Does any of you have any experience with having a mouse infestation at home? My best friend has young children and had to move to stay with family last week after calling pest control out to deal with a mouse problem. They put lots of trays of mouse poison in the affected rooms and one of the trays was emptied (eaten) a couple of days later. None of the others have been touched. But the pest controller put some poison down a hole in the floorboards too. All has been quiet since then. Does it seem they might have died/disappeared? How long does it take to get rid of mice? The pest control will come back next week to check. Of course he knows all about keeping the trays away from the child, we are just curious why only 1 of about 12 or 13 have been eaten!
Thanks in advance!