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如样本来自某总体,χ2值小于3.84时,样本率来自总体率的概率是()。
A . 99%
B . 95%
C . <1.0%
D . >5.0%
E . <5.0%
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如样本来自某总体,χ2值小于3.84时,样本率来自总体率的概率是()
A . A.99%
B . B.95%
C . C.<1.0%
D . D.>5.0%
E . E.<5.0%
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如样本来自某总体,
https://assets.asklib.com/psource/2015092814315241229.jpg
值小于3.84时,样本率来自总体率的概率是()。
A . 99%
B . 95%
C . <1.0%
D . >5.0%
E . <5.0%
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设总体X~N(μ,μ<sup>2</sup>),基于来自总体X的容量为16的简单随机样本,测得样本均=31.645,样本方差s<sup>2</sup>=0.09,则总体均值μ的置信度为0.98的置信区间为()。
A.(30.88,32.63)
B.(31.45,31.84)
C.(31.62,31.97)
D.(30.45,31.74)
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设 为来自总体N(μ,σ2)的简单随机样本, 为样本均值,已知 是σ<sup>2</sup>的无偏估计(或ET=σ<sup>2</sup>),
设<img src='https://img2.soutiyun.com/ask/2020-11-18/974563559946235.png' />为来自总体N(μ,σ2)的简单随机样本,<img src='https://img2.soutiyun.com/ask/2020-11-18/974563569546784.png' />为样本均值,已知<img src='https://img2.soutiyun.com/ask/2020-11-18/974563615737426.png' />是σ<sup>2</sup>的无偏估计(或ET=σ<sup>2</sup>),则常数C必为()
A.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563625160965.png' />
B.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563634424495.png' />
C.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563643532016.png' />
D.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563651352464.png' />
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设是来自总体N(μ,σ<sup>2</sup>)的容量为n的两个相互独立的简单随机样本的均值,试确定n.使得两个样
设<img src='https://img2.soutiyun.com/ask/2020-10-05/970778702595939.jpg' />是来自总体N(μ,σ<sup>2</sup>)的容量为n的两个相互独立的简单随机样本的均值,试确定n.使得两个样本均值之差的绝对值超过σ的概率大约为0.01.
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设X<sub>1</sub>,X<sub>2</sub>,...X<sub>20</sub>是来自正态总体N(0,0.3<sup>2</sup>)的一个样本,求:
设X<sub>1</sub>,X<sub>2</sub>,...X<sub>20</sub>是来自正态总体N(0,0.3<sup>2</sup>)的一个样本,求:
<img src='https://img2.soutiyun.com/ask/2020-07-31/965060656688145.png' />
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设X<sub>1</sub>,X<sub>2</sub>,...X<sub>n</sub>(n≥2)为来自正态总体N(0,1)的简单随机样本,为样本均值,S<sup>2</sup>为样
设X<sub>1</sub>,X<sub>2</sub>,...X<sub>n</sub>(n≥2)为来自正态总体N(0,1)的简单随机样本,<img src='https://img2.soutiyun.com/ask/2020-07-31/965062468168756.png' />为样本均值,S<sup>2</sup>为样本方差,则正确的是()。
<img src='https://img2.soutiyun.com/ask/2020-07-31/965062477119268.png' />
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设总体X的分布律为P{X=x}=p(1-p)<sup>i-1</sup>,x=1,2,3,..,X<sub>1</sub>,X<sub>2</sub>,...,X<sub>n</sub>是来自总体X的样本,试求:(1)p的矩估计量;(2)P的最大似然估计量.
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设χ<sub>1</sub>,χ<sub>2</sub>,…,χ<sub>n</sub>是来自正态总体N(μ,σ<sup>2</sup>)的一个样本,求参数μ,σ<sup>2</sup>的矩估计量.
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设 是来自总体X~N(μ,σ<sup>2</sup>)的样本,其中μ已知,σ<sup>2</sup>>0为未知参数,样本均值为 ,则σ<sup>2</sup>
设<img src='https://img2.soutiyun.com/ask/2020-11-18/974563559946235.png' />是来自总体X~N(μ,σ<sup>2</sup>)的样本,其中μ已知,σ<sup>2</sup>>0为未知参数,样本均值为<img src='https://img2.soutiyun.com/ask/2020-11-18/974563569546784.png' />,则σ<sup>2</sup>的最大似然估计量为()
A.<img src='https://img2.soutiyun.com/ask/2020-11-18/97456369359988.png' />
B.<img src='https://img2.soutiyun.com/ask/2020-11-18/97456370198636.png' />
C.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563711307893.png' />
D.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563720210402.png' />
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设X<sub>1</sub>,X<sub>2</sub>,X<sub>3</sub>,X<sub>4</sub>是来自正态总体N(0,3<sup>2</sup>)的简单随机样本,若随机变量<img src='https://img2.soutiyun.com/shangxueba/ask/51402001-51405000/51404692/978102656256342.jpg' />,试求a,b的值,使统计量X服从χ<sup>2</sup>分布,并求其自由度。
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设X<sub>1</sub>,X<sub>2</sub>,...,X<sub>15</sub>是来自正态总体X~N(0,2<sup>2</sup>)的样本,记,求Y的分布。
设X<sub>1</sub>,X<sub>2</sub>,...,X<sub>15</sub>是来自正态总体X~N(0,2<sup>2</sup>)的样本,记<img src='https://img2.soutiyun.com/ask/2020-11-26/97524949946665.jpg' />,求Y的分布。
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设 是来自总体X~N(μ,σ<sup>2</sup>)的简单随机样本,记求(I)E(Y);(II)D(Y).
设<img src='https://img2.soutiyun.com/ask/2020-11-18/974556250959185.png' />是来自总体X~N(μ,σ<sup>2</sup>)的简单随机样本,记<img src='https://img2.soutiyun.com/ask/2020-11-18/974556263092879.png' />
求(I)E(Y);
(II)D(Y).
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四个样本率作比较,χ<sup>2</sup>>χ<sup>2</sup>0.01(3),可以认为()
A.各总体率不同或不全相同
B.各总体率均不相同
C.各样本率均不相同
D.各样本率不同或不全相同
E.样本率与总体率均不相同
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x<sub>1</sub>,x<sub>2</sub>,…,x<sub>3</sub>是来自总体N(μ,0.3<sup>2</sup>)的样本值,且样本的均值=21.8.则μ的置信度为0
x<sub>1</sub>,x<sub>2</sub>,…,x<sub>3</sub>是来自总体N(μ,0.3<sup>2</sup>)的样本值,且样本的均值<img src='https://img2.soutiyun.com/ask/2020-09-30/97034316026152.png' />=21.8.则μ的置信度为0.95的置信区间为().
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设总体X~N(0,σ<sup>2</sup>),X<sub>1</sub>,X<sub>2</sub>,...,X<sub>n</sub>是来自总体X的一个样本.
设总体X~N(0,σ<sup>2</sup>),X<sub>1</sub>,X<sub>2</sub>,...,X<sub>n</sub>是来自总体X的一个样本.
<img src='https://img2.soutiyun.com/ask/2020-09-30/970341001201029.png' />
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设 ,是来自总体N(0,σ<sup>2</sup>)的简单随机样本,则可以构造未知参数σ<sup>2</sup>的无偏估计量(或数学
设<img src='https://img2.soutiyun.com/ask/2020-11-18/974562941547865.png' />,是来自总体N(0,σ<sup>2</sup>)的简单随机样本,则可以构造未知参数σ<sup>2</sup>的无偏估计量(或数学期望为σ<sup>2</sup>的统计量)()
A.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563028033812.png' />
B.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563036905319.png' />
C.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563044501754.png' />
D.<img src='https://img2.soutiyun.com/ask/2020-11-18/974563052164192.png' />
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设 为来自总体N(μ,σ<sup>2</sup>)(σ>0)的简单随机样本;令 则()A.B.C.D.
设<img src='https://img2.soutiyun.com/ask/2020-11-18/974555447058205.png' />为来自总体N(μ,σ<sup>2</sup>)(σ>0)的简单随机样本;令<img src='https://img2.soutiyun.com/ask/2020-11-18/974555483547292.png' />则()
A.<img src='https://img2.soutiyun.com/ask/2020-11-18/974555514524064.png' />
B.<img src='https://img2.soutiyun.com/ask/2020-11-18/974555523007549.png' />
C.<img src='https://img2.soutiyun.com/ask/2020-11-18/974555531280022.png' />
D.<img src='https://img2.soutiyun.com/ask/2020-11-18/974555539864513.png' />
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设X<sub>1</sub>,X<sub>2</sub>,...X<sub>2n</sub>(n≥1)为来自正态总体N(1,0.5)的一个样本,求统计量Y=(X<sub>1</sub>-X<sub>2</sub>)<sup>2</sup>+(X<sub>3</sub>-X<sub>4</sub>)<sup>2</sup>+...+(X<sub>2n-1</sub>-X<sub>2n</sub>)<
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设X<sub>1</sub>,X<sub>2</sub>,...,X<sub>9</sub>是来自正态总体X~N(0,2<sup>2</sup>)的样本,求a,b,c使得:
设X<sub>1</sub>,X<sub>2</sub>,...,X<sub>9</sub>是来自正态总体X~N(0,2<sup>2</sup>)的样本,求a,b,c使得:<img src='https://img2.soutiyun.com/ask/2020-11-26/975249407058365.jpg' />
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设为来自正态总体N(0,σ<sup>2</sup>)的简单随机样本,则统计量服从的分布为()A.F(1,1)B.F(2,1)C.t(1)
设<img src='https://img2.soutiyun.com/ask/2020-11-18/974556800064592.png' />为来自正态总体N(0,σ<sup>2</sup>)的简单随机样本,则统计量<img src='https://img2.soutiyun.com/ask/2020-11-18/974556809002103.png' />服从的分布为()
A.F(1,1)
B.F(2,1)
C.t(1)
D.t(2)
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60、来自总体1的一个容量为l6的样本的方差s1²=5.8,来自总体2的一个容量为20的样本的方差s2²。在α=0.05的显著性水平下,检验假设H0:σ1≤σ2²;H1:σ1²>σ2²,得到的结论是()。
A.拒绝H0
B.不拒绝H0
C.可以拒绝也可以不拒绝H0
D.可能拒绝也可能不拒绝H0