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Chapter10-InferenceAboutMeansandProportionswithTwoPopulations
CopyrightCengageLearning.PoweredbyCognero.
Page
PAGE
MultipleChoice
1.
Ifweareinterestedintestingwhethertheproportionofitemsinpopulation1islargerthantheproportionofitemsinpopulation2,the
a.
nullhypothesisshouldstatep1-p2<0.
b.
alternativehypothesisshouldstatep1-p2
=
0.
c.
alternativehypothesisshouldstatep1-p2<0.
d.
alternativehypothesisshouldstatep1-p2>0.
ANSWER:
d
2.
Tocomputeanintervalestimateforthedifferencebetweenthemeansoftwopopulations,thetdistribution
a.
isrestrictedtosmallsamplesituations.
b.
isnotrestrictedtosmallsamplesituations.
c.
canbeappliedwhenthepopulationshaveequalmeans.
d.
canbeappliedonlywhenthepopulationshaveequalstandarddeviations.
ANSWER:
b
3.
Whendevelopinganintervalestimateforthedifferencebetweentwopopulationmeanswithsamplesizesofn1andn2,
a.
n1mustbeequalton2.
b.
n1mustbesmallerthann2.
c.
n1mustbelargerthann2.
d.
n1andn2canbeofdifferentsizes.
ANSWER:
d
4.
Toconstructanintervalestimateforthedifferencebetweenthemeansoftwopopulationswhenthestandarddeviationsofthetwopopulationsareunknownanditcanbeassumedthetwopopulationshaveequalvariances,wemustuseatdistributionwith(letn1bethesizeofsample1andn2thesizeofsample2)_____degreesoffreedom.
a.
(n1+n2)
b.
(n1+n2-1)
c.
(n1+n2-2)
d.
(n1-1)
ANSWER:
c
5.
Wheneachdatavalueinonesampleismatchedwithacorrespondingdatavalueinanothersample,thesamplesareknownas_____samples.
a.
proportional
b.
matched
c.
independent
d.
pooled
ANSWER:
b
6.
Twoindependentsimplerandomsamplesaretakentotestthedifferencebetweenthemeansoftwopopulationswhosevariancesarenotknown,butareassumedtobeequal.Thesamplesizesaren1=31andn2=40.Thecorrectdistributiontouseisthe
t
distributionwith_____degreesoffreedom.
a.
73
b.
72
c.
71
d.
69
ANSWER:
d
7.
Twoindependentsimplerandomsamplesaretakentotestthedifferencebetweenthemeansoftwopopulationswhosestandarddeviationsarenotknown,butareassumedtobeequal.Thesamplesizesaren1=25andn2=30.Thecorrectdistributiontouseisthe
t
distributionwith_____degreesoffreedom.
a.
57
b.
53
c.
54
d.
56
ANSWER:
b
8.
Iftwoindependentlargesamplesaretakenfromtwopopulations,thesamplingdistributionofthedifferencebetweenthetwosamplemeans
a.
canbeapproximatedbyanydistribution.
b.
willhaveavarianceofone.
c.
canbeapproximatedbyanormaldistribution.
d.
willhaveameanofone.
ANSWER:
c
9.
Thestandarderrorof
-
isthe
a.
pooledestimatorof
-
.
b.
varianceofthesamplingdistribution
of
-
.
c.
standarddeviationofthesamplingdistribution
of
-
.
d.
marginoferror
of
-.?
ANSWER:
c
10.
Thesamplingdistributionof
-
isapproximatedbya
a.
normaldistribution.
b.
t
distributionwithn1+n2degreesoffreedom.
c.
tdistributionwithn1+n2-1degreesoffreedom.
d.
-
distribution.
ANSWER:
a
11.
Salaryinformationregardingmaleandfemaleemployeesofalargecompanyisshownbelow.
Male
Female
SampleSize
64
36
SampleMeanSalary(in$1000)
45
41
PopulationVariance()
128
72
?
Thepointestimateofthedifferencebetweenthemeansofthetwopopulationsis
a.
-28.
b.
3.
c.
4.
d.
-4.
ANSWER:
c
12.
Salaryinformationregardingmaleandfemaleemployeesofalargecompanyisshownbelow.
Male
Female
SampleSize
64
36
SampleMeanSalary(in$1000)
45
41
PopulationVariance()
128
72
?
Thestandarderrorofthedifferencebetweenthetwosamplemeansis
a.
4.
b.
7.46.
c.
4.24.
d.
2.0.
ANSWER:
d
13.
Salaryinformationregardingmaleandfemaleemployeesofalargecompanyisshownbelow.
Male
Female
SampleSize
64
36
SampleMeanSalary(in$1000)
45
41
PopulationVariance()
128
72
?
At95%confidence,themarginoferroris
a.
1.960.
b.
1.645.
c.
3.920.
d.
7.839.
ANSWER:
c
14.
Salaryinformationregardingmaleandfemaleemployeesofalargecompanyisshownbelow.
Male
Female
SampleSize
64
36
SampleMeanSalary(in$1000)
45
41
PopulationVariance()
128
72
?
The95%confidenceintervalforthedifferencebetweenthemeansofthetwopopulationsis
a.
0to6.92.
b.
-2to2.
c.
-1.96to1.96.
d.
0.08to7.92.
ANSWER:
d
15.
Salaryinformationregardingmaleandfemaleemployeesofalargecompanyisshownbelow.
Male
Female
SampleSize
64
36
SampleMeanSalary(in$1000)
45
41
PopulationVariance()
128
72
?
Ifyouareinterestedintestingwhetherornotthepopulationaveragesalaryofmalesissignificantlygreaterthanthatoffemalesatanα
=.05,theteststatisticis
a.
2.0.
b.
1.5.
c.
1.96.
d.
1.645.
ANSWER:
a
16.
Salaryinformationregardingmaleandfemaleemployeesofalargecompanyisshownbelow.
Male
Female
SampleSize
64
36
SampleMeanSalary(in$1000)
45
41
PopulationVariance()
128
72
?
Ifyouareinterestedintestingwhetherornotthepopulationaveragesalaryofmalesissignificantlygreaterthanthatoffemales,thep-valueis
a.
.0228.
b.
.0455.
ANSWER:
a
17.
Salaryinformationregardingmaleandfemaleemployeesofalargecompanyisshownbelow.
Male
Female
SampleSize
64
36
SampleMeanSalary(in$1000)
45
41
PopulationVariance()
128
72
?
Ifyouareinterestedintestingwhetherornotthepopulationaveragesalaryofmalesissignificantlygreaterthanthatoffemales,
atα
=.05,theconclusionisthatthepopulation
a.
averagesalaryofmalesissignificantlygreaterthanfemales.
b.
averagesalaryofmalesissignificantlylowerthanfemales.
c.
salariesofmalesandfemalesareequal.
d.
averagesalaryofmalesisgreaterthanfemalescannotbeproved.
ANSWER:
d
18.
Thefollowinginformationwasobtainedfrommatchedsamples
takenfromtwopopulations.
Thedailyproductionratesforasampleofworkersbeforeandafteratrainingprogramareshownbelow.
Assumethepopulationofdifferencesisnormallydistributed.
Worker
Before
After
1
20
22
2
25
23
3
27
27
4
23
20
5
22
25
6
20
19
7
17
18
?
Thepointestimateforthedifferencebetweenthemeansofthetwopopulationsis
a.
-1.
b.
-2.
c.
0.
d.
1.
ANSWER:
c
19.
Thefollowinginformationwasobtainedfrommatchedsamplestakenfromtwopopulations.
Thedailyproductionratesforasampleofworkersbeforeandafteratrainingprogramareshownbelow.
Assumethepopulationofdifferencesisnormallydistributed.
Worker
Before
After
1
20
22
2
25
23
3
27
27
4
23
20
5
22
25
6
20
19
7
17
18
?
ThenullhypothesistobetestedisH0:μd=0.Theteststatisticis
a.
-1.96.
b.
1.77.
c.
0.
d.
1.00.
ANSWER:
c
20.
Thefollowinginformationwasobtainedfrommatchedsamplestakenfromtwopopulations.
Thedailyproductionratesforasampleofworkersbeforeandafteratrainingprogramareshownbelow.
Assumethepopulationofdifferencesisnormallydistributed.
Worker
Before
After
1
20
22
2
25
23
3
27
27
4
23
20
5
22
25
6
20
19
7
17
18
?
GiventhatthenullhypothesistobetestedisH0:μd=0,
a.
thenullhypothesisshouldberejected.
b.
thenullhypothesisshouldnotberejected.
c.
thealternativehypothesisshouldberevised.
d.
thenullhypothesisshouldberevised.
ANSWER:
b
21.
Astatisticsteacherwantstoseeifthereisanydifferenceintheabilitiesofstudentsenrolledinstatisticstodayandthoseenrolledfiveyearsago.Asampleoffinalexaminationscoresfromstudentsenrolledtodayandfromstudentsenrolledfiveyearsagowastaken.Youaregiventhefollowinginformation.
Today
FiveYearsAgo
82
88
σ2
112.5
54
n
45
36
?
Thepointestimateforthedifferencebetweenthemeansofthetwopopulationsis
a.
58.5.
b.
9.
c.
-9.
d.
-6.
ANSWER:
d
22.
Astatisticsteacherwantstoseeifthereisanydifferenceintheabilitiesofstudentsenrolledinstatisticstodayandthoseenrolledfiveyearsago.Asampleoffinalexaminationscoresfromstudentsenrolledtodayandfromstudentsenrolledfiveyearsagowastaken.Youaregiventhefollowinginformation.
Today
FiveYearsAgo
82
88
σ2
112.5
54
n
45
36
?
Thestandarderrorof
-
is
a.
12.9.
b.
9.3.
c.
4.
d.
2.
ANSWER:
d
23.
Astatisticsteacherwantstoseeifthereisanydifferenceintheabilitiesofstudentsenrolledinstatisticstodayandthoseenrolledfiveyearsago.Asampleoffinalexaminationscoresfromstudentsenrolledtodayandfromstudentsenrolledfiveyearsagowastaken.Youaregiventhefollowinginformation.
Today
FiveYearsAgo
82
88
σ2
112.5
54
n
45
36
?
The98%confidenceintervalforthedifferencebetweenthetwopopulationmeansis
a.
-9.92to-2.08.
b.
-10.66to-1.34.
c.
-13.84to-1.16.
d.
-24.77to12.23.
ANSWER:
b
24.
Astatisticsteacherwantstoseeifthereisanydifferenceintheabilitiesofstudentsenrolledinstatisticstodayandthoseenrolledfiveyearsago.Asampleoffinalexaminationscoresfromstudentsenrolledtodayandfromstudentsenrolledfiveyearsagowastaken.Youaregiventhefollowinginformation.
Today
FiveYearsAgo
82
88
σ2
112.5
54
n
45
36
?
Theteststatisticforthedifferencebetweenthetwopopulationmeansis
a.
-.47.
b.
-.65.
c.
-1.5.
d.
-3.0.
ANSWER:
d
25.
Astatisticsteacherwantstoseeifthereisanydifferenceintheabilitiesofstudentsenrolledinstatisticstodayandthoseenrolledfiveyearsago.Asampleoffinalexaminationscoresfromstudentsenrolledtodayandfromstudentsenrolledfiveyearsagowastaken.Youaregiventhefollowinginformation.
Today
FiveYearsAgo
82
88
σ2
112.5
54
n
45
36
?
Thep-valueforthedifferencebetweenthetwopopulationmeansis
a.
.0013.
b.
.0027.
c.
.4987.
d.
.9987.
ANSWER:
b
26.
Astatisticsteacherwantstoseeifthereisanydifferenceintheabilitiesofstudentsenrolledinstatisticstodayandthoseenrolledfiveyearsago.Asampleoffinalexaminationscoresfromstudentsenrolledtodayandfromstudentsenrolledfiveyearsagowastaken.Youaregiventhefollowinginformation.
Today
FiveYearsAgo
82
88
σ2
112.5
54
n
45
36
?
Whatistheconclusionthatcanbereachedaboutthedifferenceintheaveragefinalexaminationscoresbetweenthetwoclasses?(Usea.05levelofsignificance.)
a.
Thereisastatisticallysignificantdifferenceintheaveragefinalexaminationscoresbetweenthetwoclasses.
b.
Thereisnostatisticallysignificantdifferenceintheaveragefinalexaminationscoresbetweenthetwoclasses.
c.
Itisimpossibletomakeadecisiononthebasisoftheinformationgiven.
d.
Thestudentswhoenrolledinstatisticstodayarethesamestudentswhoenrolledfiveyearsago.
ANSWER:
a
27.
Thefollowinginformationwasobtainedfromindependentrandomsamplestakenoftwopopulations.
Assumenormallydistributedpopulationswithequalvariances.
Sample1
Sample2
SampleMean
45
42
SampleVariance
85
90
SampleSize
10
12
?
Thepointestimateforthedifferencebetweenthemeansofthetwopopulationsis
a.
0.
b.
-3.
c.
3.
d.
15.
ANSWER:
c
28.
Thefollowinginformationwasobtainedfromindependentrandomsamplestakenoftwopopulations.
Assumenormallydistributedpopulationswithequalvariances.
Sample1
Sample2
SampleMean
45
42
SampleVariance
85
90
SampleSize
10
12
?
Thestandarderrorof
-
is
a.
3.0.
b.
4.
c.
8.372.
d.
19.48.
ANSWER:
b
29.
Thefollowinginformationwasobtainedfromindependentrandomsamplestakenoftwopopulations.
Assumenormallydistributedpopulationswithequalvariances.
Sample1
Sample2
SampleMean
45
42
SampleVariance
85
90
SampleSize
10
12
?
Thedegreesoffreedomforthetdistributionare
a.
22.
b.
10.
c.
24.
d.
20.
ANSWER:
d
30.
Thefollowinginformationwasobtainedfromindependentrandomsamplestakenoftwopopulations.
Assumenormallydistributedpopulationswithequalvariances.
Sample1
Sample2
SampleMean
45
42
SampleVariance
85
90
SampleSize
10
12
?
The95%confidenceintervalforthedifferencebetweenthetwopopulationmeansis(useroundedstandarderror)
a.
-5.344to11.344.
b.
-5to3.
c.
-4.86to10.86.
d.
-2.65to8.65.
ANSWER:
a
31.
Thefollowinginformationwasobtainedfrommatchedsamplestakenfromtwopopulations.
Assumethepopulationofdifferencesisnormallydistributed.
Individual
Method1
Method2
1
7
5
2
5
9
3
6
8
4
7
7
5
5
6
?
Thepointestimateforthedifferencebetweenthemeansofthetwopopulations(Method1-Method2)is
a.
-1.
b.
0.
c.
-4.
d.
2.
ANSWER:
a
32.
Thefollowinginformationwasobtainedfrommatchedsamples
takenfromtwopopulations.
Assumethepopulationofdifferencesisnormallydistributed.
Individual
Method1
Method2
1
7
5
2
5
9
3
6
8
4
7
7
5
5
6
?
The98%confidenceintervalforthedifferencebetweenthetwopopulationmeansis
a.
-3.776to1.776.
b.
-4.747to2.747.
c.
-1.776to2.776.
d.
-4.747to1.776.
ANSWER:
b
33.
Thefollowinginformationwasobtainedfrommatchedsamples
takenfromtwopopulations.
Assumethepopulationofdifferencesisnormallydistributed.
Individual
Method1
Method2
1
7
5
2
5
9
3
6
8
4
7
7
5
5
6
?
ThenullhypothesistestedisH0:μd=0.Theteststatisticforthedifferencebetweenthetwopopulationmeansis
a.
2.
b.
0.
c.
-1.
d.
-2.
ANSWER:
c
34.
Thefollowinginformationwasobtainedfrommatchedsamples
takenfromtwopopulations.
Assumethepopulationofdifferencesisnormallydistributed.
Individual
Method1
Method2
1
7
5
2
5
9
3
6
8
4
7
7
5
5
6
?
Ifthenullhypothesis
H0:μd=0istestedatthe5%level,
a.
thenullhypothesisshouldberejected.
b.
thenullhypothesisshouldnotberejected.
c.
thealternativehypothesisshouldberevised.
d.
thenullhypothesisshouldberevised.
ANSWER:
b
35.
Themanagementofadepartmentstoreisinterestedinestimatingthedifferencebetweenthemeancreditpurchasesofcustomersusingthestore'screditcardversusthosecustomersusinganationalmajorcreditcard.Youaregiventhefollowinginformation.
Store'sCard
MajorCreditCard
Samplesize
64
49
Samplemean
$140
$120
Populationstandarddeviation
$10
$8
?
Apointestimateforthedifferencebetweenthemeanpurchasesofallusersofthetwocreditcardsis
a.
20.
b.
2.
c.
260.
d.
15.
ANSWER:
a
36.
Themanagementofadepartmentstoreisinterestedinestimatingthedifferencebetweenthemeancreditpurchasesofcustomersusingthestore'screditcardversusthosecustomersusinganationalmajorcreditcard.Youaregiventhefollowinginformation.
Store'sCard
MajorCreditCard
Samplesize
64
49
Samplemean
$140
$120
Populationstandarddeviation
$10
$8
?
At95%confidence,themarginoferroris
a.
1.694.
b.
3.32.
c.
1.96.
d.
15.
ANSWER:
b
37.
Themanagementofadepartmentstoreisinterestedinestimatingthedifferencebetweenthemeancreditpurchasesofcustomersusingthestore'screditcardversusthosecustomersusinganationalmajorcreditcard.Youaregiventhefollowinginformation.
Store'sCard
MajorCreditCard
Samplesize
64
49
Samplemean
$140
$120
Populationstandarddeviation
$10
$8
?
A95%confidenceintervalestimateforthedifferencebetweentheaveragepurchasesofallcustomersusingthetwodifferentcreditcardsis
a.
13.31to16.69.
b.
11.68to18.32.
c.
12.22to17.78.
d.
16.68to23.32.
ANSWER:
d
38.
Inordertoestimatethedifferencebetweentheaveragehourlywagesofemployeesoftwobranchesofadepartmentstore,thefollowingdatahavebeengathered.
DowntownStore
NorthMallStore
Samplesize
25
20
Samplemean
$9
$8
Samplestandarddeviation
$2
$1
?
Apointestimateforthedifferencebetweenthetwopopulationmeansis
a.
1.
b.
2.
c.
3.
d.
4.
ANSWER:
a
39.
Inordertoestimatethedifferencebetweentheaveragehourlywagesofemployeesoftwobranchesofadepartmentstore,thefollowingdatahavebeengathered.
DowntownStore
NorthMallStore
Samplesize
25
20
Samplemean
$9
$8
Samplestandarddeviation
$2
$1
?
A95%intervalestimateforthedifferencebetweenthetwopopulationmeansis
a.
.071to1.929.
b.
.226to1.774.
c.
1.09to4.078.
d.
1.078to2.922.
ANSWER:
a
40.
Inordertodeterminewhetherornotthereisasignificantdifferencebetweenthemeanhourlywagespaidbytwocompanies(ofthesameindustry),thefollowingdatahavebeenaccumulated.
CompanyA
CompanyB
Samplesize
80
65
Samplemean
$16.75
$16.25
Populationstandarddeviation
$1.00
$.95
?
Apointestimateforthedifferencebetweenthetwopopulationmeansis
a.
20.
b.
.50.
c.
.25.
d.
1.00.
ANSWER:
b
41.
Inordertodeterminewhetherornotthereisasignificantdifferencebetweenthemeanhourlywagespaidbytwocompanies(ofthesameindustry),thefollowingdatahavebeenaccumulated.
CompanyA
CompanyB
Samplesize
80
65
Samplemean
$16.75
$16.25
Populationstandarddeviation
$1.00
$.95
?
Theteststatisticis
a.
.098.
b.
1.645.
c.
2.75.
d.
3.08.
ANSWER:
d
42.
Inordertodeterminewhetherornotthereisasignificantdifferencebetweenthemeanhourlywagespaidbytwocompanies(ofthesameindustry),thefollowingdatahavebeenaccumulated.
CompanyA
CompanyB
Samplesize
80
65
Samplemean
$16.75
$16.25
Populationstandarddeviation
$1.00
$.95
?
Thep-valueis
a.
.0010.
b.
.0021.
c.
.0042.
d.
.9990.
ANSWER:
b
43.
Inordertodeterminewhetherornotthereisasignificantdifferencebetweenthemeanhourlywagespaidbytwocompanies(ofthesameindustry),thefollowingdatahavebeenaccumulated.
CompanyA
CompanyB
Samplesize
80
65
Samplemean
$16.75
$16.25
Populationstandarddeviation
$1.00
$.95
?
Atthe5%levelofsignificance,thenullhypothesis
a.
shouldberejected.
b.
shouldnotberejected.
c.
shouldberevised.
d.
shouldnotbetested.
ANSWER:
a
44.
Twomajorautomobilemanufacturershaveproducedcompactcarswithenginesofthesamesize.WeareinterestedindeterminingwhetherornotthereisasignificantdifferenceinthemeanMPG(milespergallon)whentestingforthefuelefficiencyofthese
twobrandsofautomobiles.Arandomsampleofeightcarsfromeachmanufacturerisselected,andeightdriversareselectedtodriveeachautomobileforaspecifieddistance.Thefollowingdata(inmilespergallon)
showtheresultsofthetest.
Assumethepopulationofdifferencesisnormallydistributed.
Driver
ManufacturerA
ManufacturerB
1
32
28
2
27
22
3
26
27
4
26
24
5
25
24
6
29
25
7
31
28
8
25
27
?
Themeanofthedifferencesis
a.
.5.
b.
1.5.
c.
2.0.
d.
2.5.
ANSWER:
c
45.
Twomajorautomobilemanufacturershaveproducedcompactcarswith
enginesofthesamesize.WeareinterestedindeterminingwhetherornotthereisasignificantdifferenceinthemeanMPG(milespergallon)
whentestingforthefuelefficiencyofthese
twobrandsofautomobiles.Arandomsampleofeightcarsfromeachmanufacturerisselected,andeightdriversareselectedtodriveeachautomobileforaspecifieddistance.Thefollowingdata
(inmilespergallon)
showtheresultsofthetest.
Assumethepopulationofdifferencesisnormallydistributed.
Driver
ManufacturerA
ManufacturerB
1
32
28
2
27
22
3
26
27
4
26
24
5
25
24
6
29
25
7
31
28
8
25
27
?
Theteststatisticis
a.
1.616.
b.
1.906.
c.
2.096.
d.
2.256.
ANSWER:
d
46.
Twomajorautomobilemanufacturershaveproducedcompactcarswith
enginesofthesamesize.WeareinterestedindeterminingwhetherornotthereisasignificantdifferenceinthemeanMPG(milespergallon)
whentestingforthefuelefficiencyofthese
twobrandsofautomobiles.Arandomsampleofeightcarsfromeachmanufacturerisselected,andeightdriversareselectedtodriveeachautomobileforaspecifieddistance.Thefollowingdata
(inmilespergallon)
showtheresultsofthetest.
Assumethepopulationofdifferencesisnormallydistributed.
Driver
ManufacturerA
ManufacturerB
1
32
28
2
27
22
3
26
27
4
26
24
5
25
24
6
29
25
7
31
28
8
25
27
?
Atα=.10,thenullhypothesis
a.
shouldnotberejected.
b.
shouldberejected.
c.
shouldberevised.
d.
shouldnotbetested.
ANSWER:
b
47.
Theresultsofarecentpollonthepreferenceofshoppersregardingtwoproductsareshownbelow.
Product
ShoppersSurveyed
ShoppersFavoring
ThisProduct
A
800
560
B
900
612
?
Thepointestimateforthedifferencebetweenthetwopopulationproportionsinfavorofthisproductis
a.
.07.
b.
.68.
c.
.44.
d.
.02.
ANSWER:
d
48.
Theresultsofarecentpollonthepreferenceofshoppersregardingtwoproductsareshownbelow.
Product
ShoppersSurveyed
ShoppersFavoring
ThisProduct
A
800
560
B
900
612
?
Thestandarderrorof
-
is
a.
.025.
b.
.044.
c.
.0225.
d.
.68.
ANSWER:
c
49.
Theresultsofarecentpollonthepreferenceofshoppersregardingtwoproductsareshownbelow.
Product
ShoppersSurveyed
ShoppersFavoring
ThisProduct
A
800
560
B
900
612
?
At95%confidence,themarginoferroris
a.
.064.
b.
.044.
c.
.0225.
d.
.025.
ANSWER:
b
50.
Theresultsofarecentpollonthepreferenceofshoppersregardingtwoproductsareshownbelow.
Product
ShoppersSurveyed
ShoppersFavoring
ThisProduct
A
800
560
B
900
612
?
The95%confidenceintervalestimateforthedifferencebetweenthepopulationsfavoringtheproductsis
a.
-.024to.064.
b.
.6to.7.
c.
-.024to.7.
d.
.046to.066.
ANSWER:
a
51.
Aninsurancecompanyselectedsamplesofclientsunder18yearsofageandover18andrecordedthenumberofaccidentstheyhadinthepreviousyear.Theresultsareshownbelow.
UnderAgeof18
OverAgeof18
n1=500
n2=600
Numberofaccidents=180
Numberofaccidents=150
?
Weareinterestedindeterminingiftheaccidentproportionsdifferbetweenthetwoagegroups.Letpurepresenttheproportionunderandpotheproportionovertheageof18.Thenullhypothesisis
a.
pu-po≤0.
b.
pu-po≥0.
c.
pu-po≠0.
d.
pu-po=0.
ANSWER:
d
52.
Aninsurancecompanyselectedsamplesofclientsunder18yearsofageandover18andrecordedthenumberofaccidentstheyhadinthepreviousyear.Theresultsareshownbelow.
UnderAgeof18
OverAgeof18
n1=500
n2=600
Numberofaccidents=180
Numberofaccidents=150
?
Weareinterestedindeterminingiftheaccidentproportionsdifferbetweenthetwoagegroups.
Thepooledestimatorofthepopulation
proportionis
a.
.305.
b.
.300.
c.
.027.
d.
.450.
ANSWER:
b
53.
Aninsurancecompanyselectedsamplesofclientsunder18yearsofageandover18andrecordedthenumberofaccidentstheyhadinthepreviousyear.Theresultsareshownbelow.
UnderAgeof18
OverAgeof18
n1=500
n2=600
Numberofaccidents=180
Numberofaccidents=150
?
Weareinterestedindeterminingiftheaccidentproportionsdifferbetweenthetwoagegroups.Thep-valueis
a.
lessthan.001.
b.
morethan.10.
c.
.0228.
d.
.3.
ANSWER:
a
54.
Theresultsofarecentpollonthepreferenceofteenagersregardingthetypesofmusictheylistentoareshownbelow.
MusicType
TeenagersSurveyed
TeenagersFavoring
ThisType
Pop
800
384
Rap
900
450
?
Thepointestimateofthedifferencebetweenthetwopopulationproportionsis
a.
-.02.
b.
.048.
c.
.52.
d.
-.5.
ANSWER:
a
55.
Theresultsofarecentpollonthepreferenceofteenagersregardingthetypesofmusictheylistentoareshownbelow.
MusicType
TeenagersSurveyed
TeenagersFavoring
ThisType
Pop
800
384
Rap
900
450
?
The95%confidenceintervalforthedifferencebetweenthetwopopulationproportionsis
a.
.5to.52.
b.
.48to.5.
c.
.028to.068.
d.
-.068to.028.
ANSWER:
d
56.
IntestingthenullhypothesisH0:μ1
-
μ2=0,thecomputedteststatisticisz=-1.66.
Thecorrespondingp-valueis?
a.
?.0485.
b.
?.0970.
c.
?.9515.
d.
?.9030.
ANSWER:
b
57.
Ofthetwoproductionmethods,acompanywantstoidentifythemethodwiththesmallerpopulationmeancompletiontime.
Onesampleofworkersisselectedandeachworkerfirstusesonemethodandthenusestheothermethod.
Thesamplingprocedurebeingusedtocollectcompletiontimedataisbasedon?
a.
?worker
samples.
b.
?pooledsamples.
c.
?independentsamples.
d.
?matchedsamples.
ANSWER:
d
58.
Regardinginferencesaboutthedifferencebetweentwopopulationmeans,thesamplingdesignthatusesapooledsamplevarianceincasesofequalpopulationstandarddeviationsisbasedon
a.
?researchsamples.
b.
?pooledsamples.
c.
?independentsamples.
d.
conditionalsamples.
ANSWER:
c
59.
Inhypothesistestsaboutp1
-
p2,thepooledestimatorofpisa?(n)
a.
?simpleaverageof
and
?.
b.
?weightedaverageof
and.
c.
?geometricaverageof
and.
d.
?exponentialaverageof
and.
ANSWER:
b
60.
?Thesamplingdistributionof
-isapproximatedbyanormaldistributionif_____areallgreaterthanorequalto5.
a.
?n1p2,p2(1-
n2),n2p1,p1(1-
n1)
b.
?n1p1,p1(1-
n1),n2p2,p2(1-
n2)
c.
?n1p2,n1(1-
p2),n2p1,n2(1-
p1)
d.
?n1p1,n1(1-
p1),n2p2,n2(1-
p2)
ANSWER:
d
61.
Generally,the________sampleprocedureforinferencesabouttwopopulationmeansprovidesbetterprecisionthanthe_______sampleapproach.?
a.
?single,independent
b.
?independent,pooled?
c.
?matched,independent
d.
?matched,pooled
ANSWER:
c
SubjectiveShortAnswer
62.
InordertoestimatethedifferencebetweentheaverageyearlyincomesofmarketingmanagersintheEastandWestoftheUnitedStates,thefollowinginformationwasgathered.
East
West
n1=40
n2=45
=72(in$1000)
=78(in$1000)
s1=6(in$
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