统计学(第二版) 作者 张德存4 概率论基础.pptVIP

* Notation was changed to reflect Bayes?Theorem formula. Maybe, students will remember the table better. * 思考题 Thinking Challenge 情景： 3间车库，其中有一间有车。门关着，但主持人知道哪一间车库有车。 1、主持人请你挑选一间有车的车库。 2、当你选定后，主持人打开一间空车库。然后，问你是否要改变你的选择。 3、此时改变你的选择是否会增大选中有车的车库的机率？ * 选1号库 选2号库 选3号库 不变 改变 不变 改变 改变 不变 P =1/3 P =1/3 p =1/3 注：令P(选中) = p, 假定: 车在1号库, 其他情况可类推 P(不变/选2)= 0 P(改变/选3)=1 P(改变/选2)=1 P(不变/选1)=1 P(改变/选1)= 0 P(不变/选3)= 0 * 概率计算 P(不变）＝P(选1)P(不变/选1) +P(选2)P(不变/选2) + P(选3)P(不变/选3) = (1/3)(1) + (1/3)(0) + (1/3)(0) = 1/3 P(改变）＝P(选1)P(改变/选1) +P(选2)P(改变/选2) + P(选3)P(改变/选3) = (1/3)(0) + (1/3)(1) + (1/3)(1) = 2/3 * * As a result of this class, you will be able to ... * * * * * * * * Other compound events could be formed: Tail on the second toss {HT, TT} At least 1 Head {HH, HT, TH} * To be consistent with the Berenson Levine text, a simple event is shown. Typically, this is not considered an event since it is not an outcome of the experiment. * * * * * * * Try other examples using this table. * * * Try other examples using this table. * * * * Try other examples using this table. * * * You抮e a new bank loan officer. Being new, you think that there抯 a 50% chance of a loan applicant repaying a loan. Mary is applying for a loan. What is the probability that she repays? You check bank records get the table. Mary is a college graduate. Now, what is the probability that she repays the loan? * * 概率论基础Basic Probability 在线教务辅导网： 教材其余课件及动画素材请查阅在线教务辅导网 QQ:349134187 或者直接输入下面地址： * 学习目标 Learning Objectives 1. 定义事件、样本空间和概率Define Events, Sample Space, Probability 2. 解释如何确定概率和应用概率规则Explain How to Assign Probabilities and Use Probability Rules 3. 应用贝叶斯定理Use Bayes’ Theorem * 事件和样本空间 Events and Sample Spaces 1. 简单事件 Simple Event 结果只具有一个特征 2. 联合事件 Joint Event 两个事件同时发生 3. 复合事件 Compound Event 一件事发生或者另一件事发生 4. 样本空间: Sample Space 全体事件结果的集合 * 简单事件 Simple Event A: 女性 B: 不到 20 岁, 20