







































































Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
MATH 225N MATH Statistic Final MATH 225N MATH Statistic Final MATH 225N MATH Statistic Final
Typology: Exams
1 / 79
This page cannot be seen from the preview
Don't miss anything!








































































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.
H 0 :X≤ 7. 4 ,Ha:X> 7.
Correctanswer:
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: ATypeIIerroristhedecisionnottorejectthenulhypothesiswhen,infact,itisfalse.In thiscase,theTypeIIerroriswhenthebuildinginspectorthinksthatnomore
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 thepopulationmeanweightto 4 ounces.So,thisvalue(foundinthenulandalternative
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?
$$Test_Statistic=−0.
Findtheteststatisticforthishypothesistestforaproportion.Roundyouranswer
AnswerExplanation
Correctanswers:
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.
$$P-value=0.
ThefolowingtablecanbeutilizedwhichprovidesareasundertheStandardNormal Curve: z 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.
Correctanswers: Herearethestepsneededtocalculatethep-valueforahypothesistestforaproportion: 1 .Determineifthehypothesistestislefttailed,righttailed,ortwotailed. 2 .Computethevalueoftheteststatistic. 3 .Ifthehypothesistestislefttailed,thep-valuewilbetheareaunderthestandard normalcurvetotheleftoftheteststatistic z 0 Ifthetestisrighttailed,thep-valuewilbetheareaunderthestandardnormal curvetotherightoftheteststatistic z 0 Ifthetestistwotailed,thep-valuewilbetheareatotheleftof−| z 0 |plusthe areatotherightof| z 0 |underthestandardnormalcurve
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.
Correctanswer: Tocometoaconclusionandinterprettheresultsforahypothesistestforproportion usingtheP-ValueApproach,thefirststepistocomparethep-valuefrom thesample datawiththelevelofsignificance. Thedecisioncriteriaisthenasfolows:
hypothesisshouldberejected.
Whenwehavemadeadecisionaboutthenulhypothesis,itisimportanttowritea thoughtfulconclusionaboutthehypothesesintermsofthegivenproblem'sscenario. Assumingtheclaim isthenulhypothesis,theconclusionisthenoneofthefolowing:
enoughevidencetorejecttheclaim.
thereisnotenoughevidencetorejecttheclaim. Assumingtheclaim isthealternativehypothesis,theconclusionisthenoneofthe folowing:
H 0 : p = 0.5 ;Ha: p≠0.5 ,whichisatwo-tailedtest.
Correctanswer:
Thenulhypothesisshouldbetrueproportion:H 0 :p=0.5.Beckywantstoknowif thetrueproportionofheadsisdifferentfrom 0.5.Thismeansthatwejustwanttotestif theproportionisnot0.5.So,thealternativehypothesisisHa:p≠0.5,whichisatwo-
tailedtest.
Johnownsacomputerrepairservice.Foreachcomputer,he
amountofmoneyJohnearnspercomputerisy= 50 + 45 x.Whatarethe independentanddependentvariables?Whatisthey-interceptandtheslope?
Theindependentvariable(x)istheamountoftimeJohnfixesacomputer.The dependentvariable(y)istheamount,indolars,Johnearnsforacomputer. Johnchargesaone-timefeeof$50 (thisiswhenx= 0 ),sothey-interceptis 50 .John earns$45 foreachhourheworks,sotheslopeis 45. Theindependentvariable(x)istheamount,indolars,Johnearnsforacomputer.The dependentvariable(y )istheamountoftimeJohnfixesacomputer. Johnchargesaone-timefeeof$45 (thisiswhenx= 0 ),sothey-interceptis 45 .John earns$50 foreachhourheworks,sotheslopeis 50. Theindependentvariable(x)istheamount,indolars,Johnearnsforacomputer.The dependentvariable(y )istheamountoftimeJohnfixesacomputer.
dependentvariable(y)istheamount,indolars,Johnearnsforacomputer. Johnchargesaone-timefeeof$ 50 (thisiswhenx= 0 ),sothey-interceptis 50. Johnearns$ 45 foreachhourheworks,sotheslopeis 45.
Johnchargesaone-timefeeof$50 (thisiswhenx= 0 ),sothey-interceptis 50 .John earns$45 foreachhourheworks,sotheslopeis 45. Theindependentvariable(x)istheamountoftimeJohnfixesacomputer.The dependentvariable(y)istheamount,indolars,Johnearnsforacomputer. Johnchargesaone-timefeeof$45 (thisiswhenx= 0 ),sothey-interceptis 45 .John earns$50 foreachhourheworks,sotheslopeis 50.
Correctanswer:
thevaluethatchanges.Hemayworkdifferentamountspercomputer,andhisearnings aredependentonhow manyhoursheworks.Thisiswhytheamount,indolars,John
They-interceptis 50 (b= 50 ).Thisishisone-timefee.Theslopeis 45 (a = 4 5 ).
Thisistheincreaseforeachhourheworks.
Arianakeepstrackoftheamountoftimeshestudiesandthescoreshegetsonher quizzes.Thedataareshowninthetablebelow.Whichofthescatterplotsbelow accuratelyrecordsthedata? Hoursstudying Quizscore 1 5 2 5 3 7
AscatterplothasahorizontalaxislabeledHoursstudyingfrom 0 to 10 inincrementsof 2 andaverticalaxislabeledQuizscorefrom 0 to 6 inincrementsof 1 .Thefolowing pointsareplotted:left-parenthesis 5 comma 1 right-parentheses;left-parenthesis 5 comma 2 right-parentheses;left-parenthesis 7 comma 3 right-parentheses;left- parenthesis 9 comma 4 right-parentheses;left-parenthesis 9 comma 5 right- parentheses.Alvaluesareapproximate.
AscatterplothasahorizontalaxislabeledHoursstudyingfrom 0 to 6 inincrementsof 1 andaverticalaxislabeledQuizscorefrom 0 to 9 inincrementsof 1 .Thefolowing pointsareplotted:left-parenthesis 1 comma 5 right-parentheses;left-parenthesis 2 comma 5 right-parentheses;left-parenthesis 3 comma 7 right-parentheses;left- parenthesis 4 comma 8 right-parentheses;left-parenthesis 5 comma 8 right- parentheses. AscatterplothasahorizontalaxislabeledHoursstudyingfrom 0 to 6 inincrementsof 1 andaverticalaxislabeledQuizscorefrom 0 to 12 inincrementsof 2 .Thefolowing pointsareplotted:left-parenthesis 1 comma 5 right-parentheses;left-parenthesis 2 comma 5 right-parentheses;left-parenthesis 3 comma 8 right-parentheses;left- parenthesis 4 comma 8 right-parentheses;left-parenthesis 5 comma 11 right- parentheses.Alvaluesareapproximate.
Correctanswer: