the principal of a school gives different certificates of award to 5 students in an assembly. because of clerical mistake, all the certificates are given in a random order. find the probability that
(a) at least 3 certificates are given correctly,
(b) all certificates are given wrongly
ans
(a) 11/120
(b) 11/30
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maths&stat - probability 一題
2006-11-20 2:10 am
回答 (1)
2006-11-20 11:29 am
✔ 最佳答案
(a) P(3) = [ 5! / (5-3)! 3! ] (percentage of who gets award to the 3rd power) (percent of who doesn't get it to the 2nd power)P(4) = [ 5! / (5-4)! 4! ] (percent to 4th) (percent to 1st power)
P(5) = [ 5! / (5-3)! 3! ] (percent to 5th) (percent to 0 power)
(b) Binompdf (totally students in assembly, percent of who gets it, 0)
you need the total number of students to get the answer
收錄日期: 2021-04-13 00:30:06
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