作者: richands (湛藍水色) 看板: GMAT
標題: [計量] JJ 46
時間: Mon Jun 15 15:22:47 2009

Q46: (Lu: This question maintains a water-tight logic!)
The probability that event A will not occur is 0.8.  The probability that
event B will not occur is 0.6.  The probability that neither event A nor
event B will not occur is 0.  What is the probability that one of the two
events of event A and event B will occur?
Answer Choices: 2/5, 3/5, 12/25 …

ANS:3/5

Note from Lu:
From “The probability that neither event A nor event B will not occur is 0.”
 → Neither A nor B will occur = 0.4 → This guarantees that “A Occurs” and
“B Occurs” are two completely separate sets that have no overlapping area.


但CD上有人這樣說

A發生= 1 – 0.8 = 0.2
B發生= 0.4              因為AB都不發生的狀況不存在，所以AB有交集，

AB = 1/5 * 2/5 = 2/25  A非B非 = 0
所以1 – AB – A非B非 = 23/25

大家覺得是哪個呢？

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◆ From: 163.14.35.108
※ 編輯: richands        來自: 163.14.35.108        (06/15 15:54)
推 blake618:A發生和B發生應該有交集