Chapter 3.2（课件）- 《统计学基础（英文版）》同步教学（人民大学版）

Chapter Probability 3 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. 1 Larson/Farber 6th ed Chapter 1 Chapter Outline 3.1 Basic Concepts of Probability and Counting 3.2 Conditional Probability and the Multiplication Rule 3.3 The Addition Rule 3.4 Additional Topics in Probability and Counting 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Section 3.2 Conditional Probability and the Multiplication Rule . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Section 3.2 Objectives How to find the probability of an event given that another event has occurred How to distinguish between independent and dependent events How to use the Multiplication Rule to find the probability of two events occurring in sequence and to find conditional probabilities . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Conditional Probability Conditional Probability The probability of an event occurring, given that another event has already occurred Denoted P(B | A) (read “probability of B, given A”) . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Example: Finding Conditional Probabilities Two cards are selected in sequence from a standard deck. Find the probability that the second card is a queen, given that the first card is a king. (Assume that the king is not replaced.) Solution: Because the first card is a king and is not replaced, the remaining deck has 51 cards, 4 of which are queens. . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Example: Finding Conditional Probabilities The table shows the results of a survey in which 2276 social media users were asked whether they have ever been offended by something they saw on social media. Find the probability that a user is male, given that the user was offended by something on social media. (Adapted from The Harris Poll) Have you ever been offended by something on social media? Yes No Total Female 619 549 1168 Male 532 576 1108 Total 1151 1125 2276 . 1 Copyright 2019, 2015, 2012, Pearson Educatio