In a class, two questions are asked.
5/7 of the students got the first one correct, 9/13 got the second correct.
Of those students who got the first one correct, 4/9 got the second one correct.
One student was chosen at random from the class.
1. given that the student got the 2nd problem correct, find the prob.that the 1st answer was correct.
2.given that the student got the 2nd problem incorrect, find the prob. that the 1st answer was correct.
THANK YOU!
probability!!!!!!!!!!
2007-04-09 9:14 am
回答 (1)
2007-04-09 10:38 am
✔ 最佳答案
C-correct W-wrong/incorrect1.P(1C2C)=5/7*4/9=20/63
P(1C2C | 2C)=(20/63)/(9/13)
=(20*13)/(63*9)
=260/567
2.P(1C2W)=5/7*5/9=25/63
P(1C2W | 2W)=(25/63)/(4/13)
=(25*13)/(63*4)
=325/252>1
It is not a possible answer because your question is not possible
In your question, P(1C2W)=25/63=0.3968>P(2W)=4/13=0.3076
即係第1條correct及第2條incorrect o既人仲多過只需第2條incorrect 的人
3. In normal case, it is equal to (1-answer of 2)
收錄日期: 2021-04-12 17:34:19
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