This book is designed to introduce the reader to some fundamental ideas about probability. It is assumed that the reader has completed chapters 1 to 7 of SMSG Introduction to Probability, Part 1. While the book is designed for junior high school students, some elementary algebra is required for a number of the exercises. The difficult exercises are marked to assist students and teachers. Chapters included are: (8) Bayes' Formula; (9) Bernoulli Trials; (10) Mathematical Expectation; (11) Bertrand's Ballot Problem; and (12) Markov Chains. Answers to exercises and additional materials are included in the appendices. (RH)