Well according to a big master in my university. After answering the ones you know you just click answers in this order a)a) b)b) c)c) and then d)d) he says you have a 50% chance of passing. That's how he is going through economics bachelor (and he is in 2nd year)!
today I actually tried it cause I didn't remember I was having a test.
Ok I didn't risk it all, I already had a 18 and a 17 (from 0 to 20) and the worst grade is droped, so it seemed like the perfect opportunity to try this theory.
(21 dec 2010) yes I received a 13.3 not bad.. And the wrong ones were the ones I thought about..to the other questions I applied this theory! good luck!