Prove that for any events A and B P(A ∪ B) = P(A) + P(B) - P(A ∩ B).?
2015-11-28 2:02 pm
Just as the difference rule gives rise to a formula for the probability of the complement of an event, so the addition and inclusion/exclusion rules give rise to formulas for the probability of the union of mutually disjoint events and for a general union of (not necessarily mutually exclusive) events.
回答 (1)
2015-11-28 2:05 pm
Draw a Venn diagram of two circles A, B overlapping. To count the area take the sum of the areas, and subtract off the overlap so as not to count that part twice. That is it! You can make it more formal, but it hardly adds anything.
收錄日期: 2021-04-21 15:28:08
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151128060222AAcuQ8c