Riddles, brain puzzles and mathematical problems

[BAndrew]

MyRedNeptune's, but the solutions are pretty similar.

You won't determine the bottle with the poison with only the last rat. It's the pattern of rats that will die that will help you. Maybe illustating the problem will help you? I don't quite understand what you don't get. Try doing it practically. Let's pick up random rats that are going to die and you will see that if you process the information (using one of the two methods) you will end up with a single bottle.

So who here is good at CS?

Assuming CS means computer science (and not counter strike or something else) then I am in some extent, but however all I know are things I read on my own on the net. I am not expert and have not completed a course.