第七章参数估计

单选

（）

A 1 B <img src="https://www.beizhujiaoyu.com/uploads/202208/16122352678681.png" width="20" height="52" /> C -<img src="https://www.beizhujiaoyu.com/uploads/202208/161223527327651.png" width="20" height="52" /> D -1

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设总体X服从[0，θ]上的均匀分布(θ>0)，x1，x2，…，xn是来自该总体的样本，为样本均值，则θ的矩估计=（）

A 2<img src="https://www.beizhujiaoyu.com/uploads/202208/161223531741721.png" width="17" height="37" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/16122353222541.png" width="17" height="37" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/161223532866791.png" width="20" height="64" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/161223533553821.png" width="32" height="60" />

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设x1，x2，…，xn1与y1，y2，…，yn2分别是来自总体N(μ1，σ2)与(μ2，σ2)的两个样本，它们相互独立，且，分别为两个样本的样本均值，则-所服从

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161223536491301.png" width="187" height="34" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/161223536863451.png" width="187" height="34" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/161223537655411.png" width="187" height="34" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/161223538259751.png" width="187" height="34" />

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设总体X～N(μ，σ2)，x1，x2，…，xn为来自总体X的样本，μ，σ2均未知，则σ2的无偏估计是（）

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161223542121951.png" width="135" height="39" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/161223542595411.png" width="111" height="39" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/161223543028461.png" width="112" height="39" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/16122354368441.png" width="134" height="39" />

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A <img src="https://www.beizhujiaoyu.com/uploads/202208/161223544548081.png" width="20" height="40" />1 B <img src="https://www.beizhujiaoyu.com/uploads/202208/161223545088301.png" width="20" height="40" />2 C <img src="https://www.beizhujiaoyu.com/uploads/202208/161223545088301.png" width="20" height="40" />3 D <img src="https://www.beizhujiaoyu.com/uploads/202208/161223545088301.png" width="20" height="40" />4

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设x1，x2，…，xn为来自总体X的样本，x为样本均值，则样本方差s2=

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161223547237311.png" width="112" height="39" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/1612235478821.png" width="135" height="38" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/161223548553531.png" width="134" height="44" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/161223549134101.png" width="135" height="39" />

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用天平称量某物体的质量9次，得平均值=15．4 g，已知天平称量结果为正态分布，其标准差为0．1 g，则该物体质量的0.95置信区间是(已知u0.025=1．9

A [14．3347，14．4653] B [15．3347，15．4653] C [14．4506，16．6543] D [13．3347，13．4766]

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从总体X中抽取样本x1，x2，…，xn，若E(X)=μ，D(X)=σ2，下列统计量中是μ的无偏估计量的为

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161223619563511.png" width="56" height="42" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/161223620259201.png" width="80" height="39" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/16122362072811.png" width="79" height="42" /> D <img src="https://www.beizhujiaoyu.com/uploads/202208/16122362127841.png" width="56" height="39" />

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极大似然估计（）

A 必然是矩估计 B 是使似然函数取得极大值的点 C 必然是二阶中心矩 D 必然是无偏估计

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总体X～N(μ，σ2)，x1，x2，x3为样本，若是未知参数μ的无偏估计，则a=（）

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161223697852211.png" width="20" height="52" /> B <img src="https://www.beizhujiaoyu.com/uploads/202208/161223698572691.png" width="19" height="52" /> C <img src="https://www.beizhujiaoyu.com/uploads/202208/161223699498451.png" width="20" height="52" /> D 1

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