8 Questionnew2.docx

8 Questionnew2.docx

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8Questionnew2

1.Aresearcherwishestodeterminewhetherthesalariesofprofessionalnursesemployedbyprivatehospitalsarehigherthanthoseofnursesemployedbygovernment-ownedhospitals.Sheselectsasampleofnursesfromeachtypeofhospitalandcalculatesthemeansandstandarddeviationsoftheirsalaries.At

cansheconcludethattheprivatehospitalspaymorethanthegovernmenthospitals?

Assumethatthevariancesareequal.

2.Asampleof100studentsatauniversityshowedthat43hadtakenoneormoreremedialcollegecourses.Asampleof200studentsatajuniorcollegeshowedthat90hadtakenoneormoreremedialcollegecourses.At

testthehypothesisthatthereisnodifferenceintheproportionofstudentswhocompleteremedialcoursesatauniversityorajuniorcollege.

3.Asampleof50familiesinwhichbothparentsworkedshowedthat36%enrolledtheirchildreninapreschool.Asampleof80familiesinwhichonlyoneparentwasemployedshowedthat25%enrolledtheirchildreninpreschool.Isthereasignificantdifferenceinthesetwoproportions?

Usethe0.01significancelevel.

4.Apresidentofalargeuniversitywishestoestimatetheaverageageofthestudentspresentlyenrolled.Frompaststudies,thestandarddeviationisknowntobe2ears.Asampleof50studentsisselected,andthemeanisfoundtobe23.2years.Findthe95%confidenceintervalofthepopulationmeans.

5.Acertainmedicationisknowntoincreasethepulserateofitsusers.Thestandarddeviationofthepulserateisknowntobe5beatsperminute.Asampleof30usershadanaveragepulserateof104beatsperminute.Findthe99%confidenceintervalofthetruemean.

6.Tenrandomlyselectedautomobileswerestopped,andthetreaddepthoftherightfronttirewasmeasured.Themeanwas0.32inch,andthestandarddeviationwas0.08inch.Findthe95%confidenceintervalofthemeandepth.

7.Thecollegepresidentasksthestatisticsteachertoestimatetheaverageageofthestudentsattheircollege.Howlargeasampleisnecessary?

Thestatisticsteacherdecidestheestimateshouldbeaccuratewithin1yearandbe99%confident.Fromapreviousstudy,thestandarddeviationoftheageswasfoundtobe2years.

8.Asampleof500nursingapplicantsincluded60frommales.Findthe90%confidenceintervalofthetrueproportionofmaleswhoappliedtothenursingprogram.

9.Inasampleof100teenagegirls,30%usedhaircoloring.Findthe95%confidenceintervalofthetrueproportionoftheteenagegirlswhousehaircoloring.

10.Aresearcherwishestoestimatewithin95%confidencethenumberofpeoplewhoownadesk-topcomputerathome.Apreviousstudyshowsthat40%ofthoseinterviewedhadadesk-topcomputerathome.Theresearcherwishestobeaccuratewithin2%ofthetrueproportion.Findtheminimumsamplesizenecessary.

11.Theresearcherwishestoestimatetheproportionofexecutiveswhoownanipad.Shewantstobe90%confidentandbeaccuratewithin5%ofthetrueproportion.Findtheminimumsamplesizenecessary.