1 / 5

Lecture 17 conditional probability

Lecture 17 conditional probability. Example : SARS Sample space, basic outcome, and event Basic rule A and B ( in both A and B) , A or B (in either A or B or both) Conditional probability of B given A =P{B|A}= P{A and B}/P{A} Probability of death for China

davin
Télécharger la présentation

Lecture 17 conditional probability

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 17 conditional probability • Example : SARS • Sample space, basic outcome, and event • Basic rule • A and B ( in both A and B) , A or B (in either A or B or both) • Conditional probability of B given A • =P{B|A}= P{A and B}/P{A} • Probability of death for China • Given a SARS death case, what is the probability that the case is from China?

  2. Class enrollment : by year and by major • Year : freshman, sophomore, junior, senior • Major, life science, social science, math science,

  3. Class enrollment : by year and by major • Year : freshman, sophomore, junior, senior • Major, life science, social science, math science, • A=freshman, B=life science • A and B = life science freshman • P(A)=30%, P(B)=35%, P(A and B)=25% • Find P(non-life science freshman) • Randomly select a student. It turns out that he/she is not • a freshman. What is the probability that he/she majors in • life science?

  4. Prisoner’s dilemma • Three prisoners , A, B, C are in jail. One of them is to be executed and the other two will be set free. Prisoner A asked the guard : one of my partners B or C will be set free. Could you please tell me which one of them will be set free? • Guard thought a while and told A : If I do not tell you, then your chance of death is 1/3. But if I tell you, then there are only two left and you are one of them to be killed. Your chance of death will be 1/2. Do you really want to increase your chance of death ?

  5. Drawers A and B • A has a good coin and a fake coin • B has two good coins and a fake coin • Open a drawer and pick a coin. • Chance of getting fake one. • Given the fake one is selected, what is the chance that it came from drawer A?

More Related