Interview - Solving problems

Hi all, I have a phone interview with 5 rings coming up. How should I prepare? I have read Heard it on the steet, and can do about 75-80% of the stat and quantitative problems in the book. On my resume, I mentioned that I have taken a class on derivatives, but I don't really remember much of it. Will I be in trouble on that account? Is solving 75% of the problems enough to get a second interview? Finally does any one know what the interview covers?

Thanks.

Edit: I just found out that it is a math/probability interview.