【一条统计与概率的英文题Supposethatwearetoobservetwoindependentrandomsamples:Y1,Y2,...,Yndenotingarandomsamplefromanormaldistributionwithmeanµ1andvarianceσ21;(2上1下）andX1,X2,...,Xmdenotingarandomsample】|小学英语问答-字典翻译问答网

问题标题：

【一条统计与概率的英文题Supposethatwearetoobservetwoindependentrandomsamples:Y1,Y2,...,Yndenotingarandomsamplefromanormaldistributionwithmeanµ1andvarianceσ21;(2上1下）andX1,X2,...,Xmdenotingarandomsample】

问题描述：

一条统计与概率的英文题

Supposethatwearetoobservetwoindependentrandomsamples:Y1,Y2,...,Yndenotingarandomsamplefromanormaldistributionwithmeanµ1andvarianceσ21;(2上1下）andX1,X2,...,Xmdenotingarandomsamplefromanothernormaldistributionwithmeanµ2andvarianceσ22（2上2下）Anapproximationforµ1

−µ2isgivenbyY−X,thediﬀerencebetweenthesamplemeans.Find

E[Y−X]

2__

andVar3(Y−X)

耿志华回答：

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