# 7-3-2 - 7-3 Part II Independent EventsExperiment flip a...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 7-3 Part II: Independent EventsExperiment: flip a coin twice•P(event A = two heads = HH) = 1/4•but suppose, before I ask the question, I reveal …•that the event “two alike” (B = {HH, TT}) has occurred?•you would say “the probability of A given Bis ½ “•written as: P(A | B) = 1/2•note: P(A) ≠P(A | B)•the information I have given you about the occurrence of event B changes P(A) from ¼ to ½ •when the known occurrence of one event changesthe probability of occurrence of another, we say that the two events are not independent•do the experiment again; now•A = head on 2ndflip , B = head on 1stflip•P(A) = ½ •but suppose I tell you that event B happened?•would that change P(A) from 1/2 to something else?•in other words, is P(A | B) = P(A)?•look: P(A | B) = P(A∩B)/P(B) = (1/4)/(1/2) = ½ •answer: no -- P(A | B) = P(A)for two events, ifthe unconditional probability = the conditional probabilitywe say the events are independent7-3 Part IIp. 1•now,...
View Full Document

{[ snackBarMessage ]}

### Page1 / 3

7-3-2 - 7-3 Part II Independent EventsExperiment flip a...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online