If you're going to take a probability exam, you can better your chances of acing the test by studying the following topics. They have a high probability of being on the exam.

The relationship between mutually exclusive and independent events

Identifying when a probability is a conditional probability in a word problem

Probability concepts that go against your intuition

Marginal, conditional, and joint probabilities for a two-way table

The Central Limit Theorem:

When to use a permutation and when to use a combination

Finding E(X) from scratch and interpreting it

Sampling with replacement versus without replacement

The Law of Total Probability and Bayes' Theorem

When the Poisson and exponential are needed in the same problem