f5數學題一問?
2011-09-24 8:09 pm
5 machines a,b,c,d and e,the system will work if machine a and at least two of the machines b,c,d and e work,probability of machine a functions normally is 0.7,probabilityof each of machines b,c,d and e is 0.6,find probability the system will function normally
回答 (1)
2011-09-25 10:36 pm
✔ 最佳答案
P(The system will function normally)= P(Machine a function normally) * P(At least two of the machines b,c,d and e work)
= P(Machine a function normally) * P(Any two of b , c , d , e work)
+ P(Machine a function normally) * P(Any three of b , c , d , e work)
+ P(Machine a function normally) * P(All of b , c , d , e work)
= 0.7 * (4C2) * 0.6² * 0.4²
+ 0.7 * (4C3) * 0.6³ * 0.4
+ 0.7 * (4C4) * 0.6⁴
= 0.24192
+ 0.24192
+ 0.09072
= 0.57456
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110924000051KK00329