大学课件-商务与经济统计习题答案（第8版，中文版）.doc

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1、StatisticalInferenceaboutMeansandProportionswithTwoPopulationsChapter10StatisticalInferenceaboutMeansandProportionswithTwoPopulationsLearningObjectives1.Beabletodevelopintervalestimatesandconducthypothesistestsaboutthedifferencebetweenthemeansoftwopopulations.2.

2、Knowthepropertiesofthesamplingdistributionofthedifferencebetweentwomeans.3.Beabletousethetdistributiontoconductstatisticalinferencesaboutthedifferencebetweenthemeansoftwonormalpopulationswithequalvariances.4.Understandtheconceptanduseofapooledvarianceestimate.5.

3、Learnhowtoanalyzethedifferencebetweenthemeansoftwopopulationswhenthesamplesareindependentandwhenthesamplesarematched.6.Beabletodevelopintervalestimatesandconducthypothesistestsaboutthedifferencebetweentheproportionsoftwopopulations.7.Knowthepropertiesofthesampli

4、ngdistributionofthedifferencebetweentwoproportions.10-19StatisticalInferenceaboutMeansandProportionswithTwoPopulationsSolutions:1.a.=13.6-11.6=2b.2±1.645(.595)2±.98(1.02to2.98)c.2±1.96(.595)2±1.17(0.83to3.17)2.a.=22.5-20.1=2.4b.c.16degreesoffreedom,t.025=2.122.4

5、±2.12(1.09)2.4±2.31(.09to4.71)3.a.b.c.=9-7=2d.e.With10degreesoffreedom,t.025=2.22810-19StatisticalInferenceaboutMeansandProportionswithTwoPopulations2±2.228(1.07)2±2.37(-0.37to4.37)4.a.=1.58-0.98=$0.60b.±z.025.60±1.96(.021).60±.04(.56to.64)5.a.22.5-18.6=3.9miles

6、perdayb.±za/222.5-18.6±1.96(1.58)3.9±3.1or0.6to7.06.LAMiami6.726.34s2.3742.1636.72-6.34±1.96(.454).38±.89or-.51to1.277.a.=14.9-10.3=4.6yearsb.z.025=1.96(.66)=1.310-19StatisticalInferenceaboutMeansandProportionswithTwoPopulationsc.±z.0254.6±1.3(3.3to5.9)8.a.=15,7

7、00-14,500=1,200b.PooledvarianceWith18degreesoffreedomt.025=2.1011200±2.101(362.88)1200±762(438to1962)c.Populationsarenormallydistributedwithequalvariances.9.a.n1=10n2=8=21.2=22.8s1=2.70s2=3.55=21.2-22.8=-1.6Kitchensarelessexpensiveby$1,600.b.±za/2Degreesoffreedo

8、m=n1+n2-2=16t.05=1.746-1.6±1.746(1.47)-1.6±2.57(-4.17to+.97)10.a.=17.54=15.3610-19StatisticalInferenceaboutMeansandProportionswithTwoPopulations=17.54-15.36=$2.18perh