Riddles, brain puzzles and mathematical problems

[Bridge]

Spoiler below!

The scientist must uncover the poison within 24 hours so the absolute minimum speed at which he can administer the medicine to the rats and still meet the deadline is ~42 bottles per hour (1000 bottles/24 hours). Since it takes 10-20 hours for the poison to kill that means the minimum amount of bottles lies somewhere between ~417 and ~833 bottles (~42 * 10 and ~42 * 20 respectively) and therefore just as many rats are required. This of course assumes he has time to check whether any rats have died after 10-20 hours while still continuing to check the bottles.

My best guess.