You don't need math skills to solve this, only problem solving skills. There are only so many ways to systematically choose 50 boxes from 100 when the only information is a name on the inside and a number on the outside.
The second link contains the math, and no way would a non-mathematician have been able to come up with that math.
http://www.mast.queensu.ca/~peter/inprocess/prisoners.pdf
edit: I agree that this does involve some math, but I like that it all can be derived from basic principles of probability.
You don't need math skills to solve this, only problem solving skills.
I'm just saying, it'd be nice if there is a warning when something that looks like a standard lateral thinking brain teaser is actually the topic of a paper submitted by a pair of professors of mathematics to the 2003 Conference on "Compexity".