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A statistical analysis of test scores, including the calculation of means, modes, and standard deviations. It also includes hypothesis testing using the t-distribution and the chi-square distribution. The data set consists of test scores for various subjects and grades.
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Afitnesscenterclaimsthatthemeanamountoftimethatapersonspendsatthegym
hypothesis,Ha,intermsoftheparameterμ.
H 0 :μ≠ 33 ;Ha:μ= 33 H 0 :μ= 33 ;Ha:μ≠ 33 H 0 :μ≥ 33 ;Ha:μ< 33 H 0 :μ≤ 33 ;Ha:μ> 33
Correctanswer:
Lettheparameterμ beusedtorepresentthemean.Thenulhypothesisisalways statedwithsomeform ofequality:equal(=),greaterthanorequalto(≥),orlessthan orequalto(≤).Therefore,inthiscase,thenulhypothesisH 0 isμ= 33 .The alternativehypothesisiscontradictorytothenulhypothesis,soHa isμ ≠ 33.
Theanswerchoicesbelowrepresentdifferenthypothesistests.Whichofthechoices areright-tailedtests?Selectalcorrectanswers.
Correctanswer:
Remembertheformsofthehypothesistests.
werebuiltwithoutpermitswhen,infact,morethan 15 % ofthestructureswerebuilt
withoutpermits. Sointhiscase,theright-tailedtestsare:
• H 0 : X≤3.8,Ha: X > 3.
thatnomorethan 15 % ofstructuresinthecountywerebuiltwithoutpermits.
Thebuildinginspectorthinksthatnomorethan 15 % ofthestructuresinthecounty werebuiltwithoutpermitswhen,infact,nomorethan 15 % ofthestructuresrealywere builtwithoutpermits. Thebuildinginspectorthinksthatmorethan 15 % ofthestructuresinthecountywere builtwithoutpermitswhen,infact,morethan 15 % ofthestructuresrealywerebuilt withoutpermits. Thebuildinginspectorthinksthatmorethan 15 % ofthestructuresinthecountywere builtwithoutpermitswhen,infact,atmost 15 % ofthestructureswerebuiltwithout permits. Thebuildinginspectorthinksthatnomorethan 15 % ofthestructuresinthecounty werebuiltwithoutpermitswhen,infact,morethan 15 % ofthestructureswerebuilt withoutpermits.
Correctanswer:
builtwithoutpermitswhen,infact,atmost 15 % ofthestructureswerebuiltwithout
permits. $$Test statistic = −2.
than 15 % ofthestructureswerebuiltwithoutpermits.
Youranswer: Content attribution- Opens a dialog
Severalofhercustomersdonotbelieveher,sothechefdecidestodoahypothesistest,
weightofthesamplemeatbalsis3.7 ounces.Thechefknowsfrom experiencethatthe standarddeviationforhermeatbalweightis0.5 ounces. • H 0 :μ ≥ 4 ;Ha:μ< 4 • α=0.1 (significancelevel) Whatistheteststatistic(z-score)ofthisone-meanhypothesistest,roundedtotwo
decimalplaces?
Correctanswers:
Thehypotheseswerechosen,andthesignificancelevelwasdecidedon,sothenext stepinhypothesistestingistocomputetheteststatistic.Inthisscenario,thesample
knowsthestandarddeviationofthemeatbals,σ=0.5.Lastly,thechefiscomparing
Astandardnormalcurvewithtwopointslabeledonthehorizontalaxis.Themeanis labeledat 0. 00 andanobservedvalueof 1. 74 islabeled.Theareaunderthecurveand totherightoftheobservedvalueisshaded.
whichistheareatotheleftofz=1.74.(StandardNormalTablesgiveareastothe left.)So,thep-valuewe'relookingforisp= 1 −0.959 =0.041.
Kenneth,acompetitorincupstacking,claimsthathisaveragestackingtime
of7. 8 secondsbasedon 11 trials.Atthe 4 % significancelevel,doesthedata
providesufficientevidencetoconcludethatKenneth'smeanstackingtimeisless
• H 0 :μ=8.2 se c o nds;Ha:μ< 8.2 seconds • α=0.04 (significancelevel) • z 0 =−1. • p=0.
significancelevelα= 0. 04.
Donotrejectthenulhypothesisbecausethep - value0.0401 isgreaterthanthe significancelevelα=0.. Rejectthenulhypothesisbecausethep - value0.0401 isgreaterthanthesignificance levelα= 0.. Rejectthenulhypothesisbecausethevalueofz isnegative. Rejectthenulhypothesisbecause|−1.75| > 0.04. Donotrejectthenulhypothesisbecause|−1.75 |>0.04.
Correctanswer:
resultsofthesampledataaresignificant.Thereissufficientevidencetoconclude
Ifα≤p-value,donotrejectH 0 .Theresultsofthesampledataarenotsignificant,so thereisnotsufficientevidencetoconcludethatthealternativehypothesis,Ha,maybe correct.Inthiscase,α= 0.04 islessthanorequaltop = 0.0401,sothedecisionis
tonotrejectthenulhypothesis.
medication.Ameliaisanurseatalargehospitalwhowouldliketoknowwhetherthe percentageisthesameforseniorcitizenpatientswhogotoherhospital.Sherandomly
them takeatleastoneprescriptionmedication.Whatarethenulandalternative hypothesesforthishypothesistest?
{H 0 :p=0.81Ha:p>0. {H 0 :p≠0.81Ha:p=0. {H 0 :p=0.81Ha:p<0. {H 0 :p=0.81Ha:p≠0.
Correctanswer:
Firstverifywhetheraloftheconditionshavebeenmet.Letp bethepopulation
proportionfortheseniorcitizenpatientstreatedatAmelia'shospitalwhotakeatleast oneprescriptionmedication.
failures,nq =n( 1 −p)=11.21,arebothgreaterthanorequalto 5.
SinceAmeliaistestingwhethertheproportionisthesame,thenulhypothesisis
Thenulandalternativehypothesesareshownbelow.
Aresearcherclaimsthattheproportionofcarswithmanualtransmissionisless
thosecars, 95 hadamanualtransmission.
Thefolowingisthesetupforthehypothesistest:
$$Test_Statistic=−0.
Findtheteststatisticforthishypothesistestforaproportion.Roundyouranswer
AnswerExplanation Correctanswers: Theproportionofsuccessesisp ^= 951000 =0.095.
Theteststatisticiscalculatedasfolows:
z=0.095−0.100.10⋅(1−0.10)1000−−−−−−−−√ z≈−0.
Amedicalresearcherclaimsthattheproportionofpeopletakingacertainmedication thatdevelopserioussideeffectsis 12 %.Totestthisclaim,arandom sampleof 900 peopletakingthemedicationistakenanditisdeterminedthat 9 3peoplehave experiencedserioussideeffects.. Thefolowingisthesetupforthishypothesistest: H 0 : p = 0. 12
Findthep-valueforthishypothesistestforaproportionandroundyouranswerto 3 decimalplaces.
Forthisexample,thetestisatwotailedtestandtheteststatistic,roundingtotwo
Thusthep-valueistheareaundertheStandardNormalcurvetotheleftofaz-scoreof
z 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.
From alookuptableoftheareaundertheStandardNormalcurve,thecorresponding areaisthen 2 ( 0. 062 )= 0. 124.
Aneconomistclaimsthattheproportionofpeoplewhoplantopurchaseafulyelectric
Totestthisclaim,arandom sampleof 750 peopleareaskediftheyplantopurchasea fulyelectricvehicleastheirnextcar Ofthese 750 people, 513 indicatethattheydo
plantopurchaseanelectricvehicle. Thefolowingisthesetupforthishypothesistest:
Inthisexample,thep-valuewasdeterminedtobe0.026.
Cometoaconclusionandinterprettheresultsforthishypothesistestforaproportion
ThedecisionistorejecttheNulHypothesis. Theconclusionisthatthereisenoughevidencetosupporttheclaim. ThedecisionistorejecttheNulHypothesis. Theconclusionisthatthereisenoughevidencetosupporttheclaim. ThedecisionistofailtorejecttheNulHypothesis. Theconclusionisthatthereisnotenoughevidencetosupporttheclaim. AnswerExplanation Correctanswer: Tocometoaconclusionandinterprettheresultsforahypothesistestforproportion usingtheP-ValueApproach,thefirststepistocomparethep-valuefrom thesample datawiththelevelofsignificance. Thedecisioncriteriaisthenasfolows:
hypothesisshouldberejected.
Whenwehavemadeadecisionaboutthenulhypothesis,itisimportanttowritea thoughtfulconclusionaboutthehypothesesintermsofthegivenproblem'sscenario. Assumingtheclaim isthenulhypothesis,theconclusionisthenoneofthefolowing:
enoughevidencetorejecttheclaim.
thereisnotenoughevidencetorejecttheclaim.
Assumingtheclaim isthealternativehypothesis,theconclusionisthenoneofthe folowing: