As in the subject, I'm interested in a math puzzle of sorts:
If stock A has a 60% chance of rising, and stocks A and B have an 80% correlation, what is the chance of stock B rising?
Would it be possible to extend this concept so that if we know the probabilities of stocks A,B,C,D rising, we can work out the probability of stock E rising, given tha stock E has some correlation to stocks A,B,C,D?
Update:
For an indepth tutorial video on the basics of probability, see the Khan Academy Tutorial Videos on Probability.