Probability Workbook For Dummies

Chapter 3

Picturing Probabilities: Venn Diagrams, Trees, and Bayes’ Theorem

IN THIS CHAPTER

Exploring Venn diagrams to organize and picture relationships

Using tree diagrams to display and work with conditional probabilities

Finding marginal probabilities using the law of total probability

Calculating conditional probabilities using Bayes’ theorem

Some probabilities are apparent from the problem, and others you have to get your hands a little dirty to work out. It’s often helpful to map out the information you are given in a problem, and use that map to find and solve the probability rules you need. In this chapter, your maps and probability rules include Venn diagrams, tree diagrams, tables, the law of total probability, and Bayes’ theorem, which come from the tree diagrams you’ve set up.

Before you start putting probabilities into picture form, it’s important to remember the difference between and and other probabilities. means the probability of A given B has occurred, so B ...