Unit 2A - Probability
        2.1 Tabular and Graphical Representations for the Distributions of Two Categorical 
              Variables
        2.2 Summary Statistics for Two Categorical Variables
        2.3 Estimating Probabilities Using Simulation
        2.4 Introduction to Probability 
        2.5 Mutually Exclusive Events
        2.6 Conditional Probability
        2.7 Independent Events and Unions of Events
        Unit 2A Review