statistics4 by kellerWord格式文档下载.docx
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statistics4 by kellerWord格式文档下载.docx
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a.Mean
b.Median
c.Mode
d.Interquartilerange
d
3.Whichmeasureofcentrallocationismeaningfulwhenthedataarenominal?
d
4.Whichmeasureofcentrallocationisappropriatewheneverwewishtofindtheaveragegrowthrate,orrateofchange,inavariableovertime?
ANSWER:
b
5.Whichofthefollowingstatementsaboutthearithmeticmeanisnotalwayscorrect?
a.Thesumofthedeviationsfromthemeaniszero
b.Halfoftheobservationsareoneithersideofthemean
c.Themeanisameasureofthemiddle(center)ofadistribution
d.Thevalueofthemeantimesthenumberofobservationsequalsthesumofallobservations
b
6.Sincethepopulationisalwayslargerthanthesample,thepopulationmean:
a.isalwayslargerthanorequaltothesamplemean
b.isalwayssmallerthanorequaltothesamplemean
c.canbesmallerthan,orlargerthan,orequaltothesamplemean
d.Noneoftheabove
c
7.Whichofthefollowingstatementsistrueforthefollowingdatavalues:
7,5,6,4,7,8,and12?
a.Themean,medianandmodeareallequal
b.Onlythemeanandmedianareequal
c.Onlythemeanandmodeareequal
d.Onlythemedianandmodeareequal
8.Inahistogram,theproportionofthetotalareawhichmustbetotheleftofthemedianis:
a.exactly0.50
b.lessthan0.50ifthedistributionisskewedtotheleft
c.morethan0.50ifthedistributionisskewedtotheright
d.between0.25and0.60ifthedistributionissymmetricandunimodal
ANSWER:
9.Whichmeasureofcentraltendencycanbeusedforbothnumericalandcategoricalvariables?
b.Themedian
c.Themode
d.Thegeometricmean
10.Whichofthemean,median,mode,andgeometricmeanareresistantmeasuresofcentraltendency?
a.Themeanandmedianonly
b.Themedianandmodeonly
c.Themodeandgeometricmeanonly
d.Themeanandmodeonly
11.Inapositively-skeweddistribution,
a.themedianequalsthemean
b.themedianislessthanthemean
c.themedianislargerthanthemean
d.themean,median,andmodeareequal
12.Whichofthefollowingstatementsaboutthemedianisnottrue?
a.Itismoreaffectedbyextremevaluesthanthemean
b.Itisameasureofcentraltendency
c.Itisequalto
d.Itisequaltothemodeinbell-shaped“normal”distributions
13.Whichofthefollowingsummarymeasuresistheeasiesttocompute?
a.Themean
d.Alloftheabove
14.Whichofthefollowingisnotameasureofcentraltendency?
d.Thefirstquartile
15.Whichofthefollowingsummarymeasuresissensitivetoextremevalues?
a.Themedian
b.Theinterquartilerange
c.Thearithmeticmean
16.Inaperfectlysymmetricalbell-shaped“normal”distribution
a.themeanequalsthemedian
b.themedianequalsthemode
c.themeanequalsthemode
17.Supposeyoumakea2–yearinvestmentof$2,500anditgrowsby100%to$5,000duringthefirstyear.Duringthesecondyear,however,theinvestmentsuffersa50%lossfrom$5,000backto$2,500.Thearithmeticmean(andthemedian)is
a.75%
b.50%
c.25%
d.0%
18.Supposeyoumakea2–yearinvestmentof$2,500anditgrowsby100%to$5,000duringthefirstyear.Duringthesecondyear,however,theinvestmentsuffersa50%lossfrom$5,000backto$2,500.Thegeometricmeanis
19.Whichofthefollowingstatementisfalse?
a.Aparameterisadescriptivemeasurementaboutapopulation
b.Astatisticisadescriptivemeasurementaboutasample
c.Studentsmaybemorefamiliarwiththeaverageastheothernameforthearithmeticmean
20.Whichofthefollowingstatementsistrue?
a.Whenthedistributionisskewedtotheleft,mean>
median>
mode
b.Whenthedistributionisskewedtotheright,mean<
median<
c.Whenthedistributionissymmetricandunimodal,mean=median=mode
d.Whenthedistributionissymmetricandbimodal,mean=median=mode
21.Inahistogram,theproportionofthetotalareawhichmustbetotherightofthemeanis
a.lessthan0.50ifthedistributionisskewedtotheleft
b.exactly0.50
d.exactly0.50ifthedistributionissymmetricandunimodal
22.Theaveragescoreforaclassof30studentswas75.The20malestudentsintheclassaveraged70.The10femalestudentsintheclassaveraged:
a.75
b.85
c.65
d.70
TRUE/FALSEQUESTIONS
23.Twoclassificationsofstatisticaldescriptionsaremeasuresofcentrallocationandmeasuresofvariability.
T
24.Themeanisoneofthemostfrequentlyusedmeasuresofvariability.
F
25.Inahistogram,theproportionofthetotalareawhichmustbetotheleftofthemedianismorethan0.50ifthedistributionisskewedtotheright.
26.Adatasamplehasameanof107,amedianof122,andamodeof134.Thedistributionofthedataispositivelyskewed.
27.Astudentscores87,73,92,and86onfourexamsduringthesemesterand95onthefinalexam.Ifthefinalisweighteddoubleandthefourothersweightedequally,thestudent'
sfinalaveragescorewouldbe90.
F
28.Inabell-shapeddistribution,thereisnodifferenceinthevaluesofthemean,median,andmode.
29.Lilyhasbeenkeepingtrackofwhatshespendstoeatout.Thelastweek'
sexpendituresformealseatenoutwere$5.69,$5.95,$6.19,$10.91,$7.49,$14.53,and$7.66.ThemeanamountLilyspendsonmealsis$8.35.
30.Inanegativelyskeweddistribution,themeanissmallerthanthemedianandthemedianissmallerthanthemode.
31.Themedianofasetofdatawouldbemorerepresentativethanthemeanofthatdatawhentheaverageofthedatavaluesislargerthanmostofthevalues.
T
32.Sincethesampleisalwayssmallerthanthepopulation,thesamplemeanisalwayssmallerthanthepopulationmean.
33.Thegeometricmeanisusefulinmeasuringtherateofchangeofavariableovertime.
34Thevalueofthemeantimesthenumberofobservationsequalsthemedianoftheobservations.
35.Inahistogram,theproportionofthetotalareawhichmustbetotheleftofthemedianislessthan0.50ifthedistributionisskewedtotheleft.
36.Themeanisameasureofthedeviationinadataset.
37.Inahistogram,theproportionofthetotalareawhichmustbetotherightofthemeanisexactly0.50ifthedistributionissymmetricandunimodal.
38.Thegeometricmeanisameasureofvariationordispersioninasetofdata.
39.Inasampleofsize50,thesamplemeanis20.Inthiscase,thesumofallobservationsinthesampleis1,000.
40.Astatisticsprofessorbaseshisfinalgradeonhomework,twomidtermexaminations,andafinalexamination.Thehomeworkcounts10%towardthefinalgrade,whileeachmidtermexaminationcounts30%.Theremainingportionconsistsofthefinalexamination.Ifastudentscored95%inhomework,75%onthefirstmidtermexamination,95%onthesecondmidtermexamination,and80%onthefinal,hisfinalaverageis84.5%.
41.Themedianofadatasetwith30itemswouldbetheaverageofthe15thandthe16thitemsintheorderedarray.
42.Thevalueofthemediantimesthenumberofobservationsequalsthesumofalloftheobservations.
43.Inapositivelyskeweddistribution,themeanislargerthanthemedianandthemedianislargerthanthemode.
44.Themedianisanappropriatemeasureofcentrallocationfornominaldata,whereasthemodeismoreappropriateforordinaldata.
STATISTICALCONCEPTS&
APPLIEDQUESTIONS
FORQUESTIONS45THROUGH47,USETHEFOLLOWINGNARRATIVE:
Narrative:
MonthlyRent
Monthlyrentdataindollarsforasampleof10one-bedroomapartmentsinasmalltowninIowaareasfollows:
220,216,220,205,210,240,195,235,204,and250.
45.{MonthlyRentNarrative}Computethesamplemonthlyaveragerent.
$219.50
46.{MonthlyRentNarrative}Computethesamplemedian.
$218
47.{MonthlyRentNarrative}Whatisthemode?
$220
FORQUESTIONS48AND49,USETHEFOLLOWINGNARRATIVE:
NumberofPets
Asampleof25familieswereaskedhowmanypetstheyowned.Theirresponsesaresummarizedinthefollowingtable.
NumberofPets
1
2
3
4
5
NumberofFamilies
10
48.{NumberofPetsNarrative}Determinethemean,themedian,andthemodeofthenumberof
petsownedperfamily.
1.80pet,median=1pet,mode=1pet
49.{NumberofPetsNarrative}Describebrieflywhateachstatistictellsyouaboutthedata.
The“average”numberofpetsownedwas1.80pets.Halfthefamiliesownatmostonepet,andtheot
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