作者hl6099 (寂寞的心)
看板trans_math
标题Re: 不知统计可以在这里问吗?徵统计解答
时间Tue Nov 8 22:52:54 2005
※ 引述《friedman911 (小咪)》之铭言：
某一工厂,生产的产品当中有15%为不良品,A从中抽出20件出来,问:
a:本题的随机变数应如何设定?
[sol]
P{X = i} = (C20取i) * (0.15)^i * (0.85)^(20 - i) i = 0,1,...,19,20
b:机率分配如何?
[sol]
Binomial distribution with (n,p) = (20,0.15)
n represents number of products
p represents the probability of fail products
c:抽出不良品中,有3件为不良品的机率有多大?
[sol]
By a,let i = 3
d:求变异数,期望值
[sol]
Expected value = n * p = 20 * 0.15 = 3
Variance = n * p * (1 - p) = 2.55
请求各位大大解答!
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