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1、IntervalEstimationChapter8IntervalEstimationLearningObjectives1.Knowhowtoconstructandinterpretanintervalestimateofapopulationmeanand/orapopulationproportion.2.Understandtheconceptofasamplingerror.3.Beabletouseknowledgeofasamplingdistributiontomakeprobabilitysta
2、tementsaboutthesamplingerror.4.Understandandbeabletocomputethemarginoferror.5.Learnaboutthetdistributionanditsuseinconstructinganintervalestimateforapopulationmean.6.Beabletodeterminethesizeofasimplerandomsamplenecessarytoestimateapopulationmeanand/orapopulatio
3、nproportionwithaspecifiedlevelofprecision.7.Knowthedefinitionofthefollowingterms:confidenceintervalprecisionconfidencecoefficientsamplingerrorconfidencelevelmarginoferrordegreesoffreedom8-13IntervalEstimationSolutions:1.a.b.At95%,2.a.32±1.64532±1.4(30.6to33.4)b
4、.32±1.9632±1.66(30.34to33.66)c.32±2.57632±2.19(29.81to34.19)3.a.80±1.9680±3.8(76.2to83.8)b.80±1.9680±2.68(77.32to82.68)c.Largersampleprovidesasmallermarginoferror.4.126±1.965.a.b.24.80±1.40or(23.40to26.20)6.±1.96369±1.96369±6.20(362.80to375.20)8-13IntervalEstim
5、ation7.±3.37±1.963.37±.05(3.32to3.42)8.a.12,000±1.64512,000±231(11,769to12,231)b.12,000±1.9612,000±275(11,725to12,275)c.12,000±2.57612,000±362(11,638to12,362)d.Intervalwidthmustincreasesincewewanttomakeastatementaboutmwithgreaterconfidence.9.a.Usingacomputer,=$
6、12.41b.Usingacomputer,s=3.64c.±1.9612.41±1.9612.41±0.92(11.49to13.33)10.7.75±.50(7.25to8.25)11.UsingMinitabweobtainedasamplestandarddeviationof2.163.Theconfidenceintervaloutputisshownbelow:THEASSUMEDSIGMA=2.16NMEANSTDEVSEMEAN95.0PERCENTC.I.Miami506.3402.1630.30
7、6(5.740,6.940)The95%confidenceintervalestimateis5.74to6.94.8-13IntervalEstimation12.a.minutesb.minutesMarginofError=minutesc.3.8±.81(2.99to4.61)13.a..95b..90c..01d..05e..95f..8514.a.1.734b.-1.321c.3.365d.-1.761and+1.761e.-2.048and+2.04815.a.b.c.With7degreesoffr
8、eedom,t.025=2.365±t.02510±2.36510±2.90(7.10to12.90)8-13IntervalEstimation16.a.17.25±1.72917.25±1.28(15.97to18.53)b.17.25±2.0917.25±1.54(15.71to18.79)c.17.25±2.86117.25±2.11(
