→ richands:感謝^^ 06/16 07:05
※ 引述《richands》之銘言：
: 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？
ANS: 3/5
這是英文問題吧...
如果題目寫neither A nor B will occur 機率=0
是 A或B都不發生的機率為0
可是請注意到他是will NOT occur
→ A與B一起發生的機率為0
A發生機率1-0.8 = 0.2
B發生機率1-0.6 = 0.4
兩者一起發生機率0
所以兩件事情中取一件發生的機率
直接相加0.2+0.4 = 0.6 = 3/5
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※ 編輯: IamNoTaStaR 來自: 61.224.46.28 (06/16 00:26)