@icelandbob: Yeah, a lot of people probably figured it out, but since I did, I might as well spoil it: That question leads in on itself in that the answer changes the answer. If the correct answer is 25%, then there's a 50% chance of getting it right since there are two 25s. If the correct answer is 50%, it changes back to being a 25% chance of getting it right. So the question is actually impossible.
It's a bit like asking "Can the answer to this question be 'no'?" Except you can solve that one with semantics by saying "you cannot" or similar.
EDIT: By the same semantic trickery, you could actually simply ignore the alternatives and answer "0%" to the problem in the picture.
@Greasemonkey, I used to work for a paper shredding company with those built into trucks. They could shred a 96 gallon bin of paper in 1:30. It was awesome.
@icelandbob: I like the Stephen King will be the end of Maine (even if they did spell his name wrong). I am, however, a little disappointed that New York City didn't get the Stay-Puft Marshmallow Man.
Did someone mention industrial shredders...? At the materials recycling facility I work at we have a number of industrial shredders, some that can eat up to 10 tonnes (22,000 lbs in old money) of material per hour - wood/plastic/paper/carpets/anything you want. That's approx 2.75kgs per second. They are a (nerdy) sight to see when in going at full tilt...