Posted by **Hailey** on Thursday, March 25, 2010 at 8:11pm.

A class is given a list of eight study problems from which five will be part of an upcoming exam. If a given student knows how to solve six of these problems, find the probability that the student will be able to answer:

(a) all five questions on the exam.

(b) exactly eight questions on the exam.

(c) at least nine questions on the exam.

No matter what I try -- permutations, combinations, random multiplying and dividing -- I can't figure any of these parts out. I don't even know where to start, really.