Sometimes, putting dependent events on a probability tree diagram is not appropriate. In this case, a Venn diagram can illustrate the information more clearly. Read in your textbook to see how a Venn diagram is used to solve a probability problem.
Recall from Unit 1 that the Textbook uses the notation A \ B which is read A minus B . It denotes the set of elements that are in set A but not in set B . It is the red region in each Venn diagram below.
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A
\
B
when
B
A
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A
\
B
when they are disjoint
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A
\
B
when they intersect
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Read pages 184-185 Example 2 in your textbook, Principles of Mathematics 12 . Complete the Your Turn question on page 185 for more practice related to dependent events. Click here to verify your answer . |
In textbook Example 2, the probability formula for dependent events is rearranged as follows.
This formula is used to find the probability of an event given the occurrence of a previous event . It is used when the intersection of A and B is known or can be found using a Venn diagram.