A math professor decided he would conduct a survey. He was studying probability and wanted to see how real people (not in academia) think in terms of probability. He stopped a man on the sidewalk and posed a question to him: "Sir, what is the probability that you will see a living dinosaur today?" The man replied, "I would say about 1 in a billion!" Interesting the professor thought. He saw a woman walking down the street and posed the same question to her: "Ma'am, what is the probability that you will see a living donosaur today?" The woman replied, "50%." The professor was rather shocked that anyone could view the odds of seeing a dinosar in 2008 as so high. He asked the woman to explain her answer. She explained, "Well, you asked what the chance is of me seeing a dinosaur today. It's 50%: I either will see one or I will not see one!"
I heard this a few weeks ago and it really made me think about the type of logic required of the GMAT.
Hope this helps brighten your day and gives you a better perspective on GMAT-type logic.