1. Whenwillthesamplingdistributionofthesamplemeanfollowanormal
distribution?
a. Whenthepopulationfollowsanormaldistribution.
b. Whenthesamplesizeislarge.
c. Bothaandb.
d. Neitheraorb.
2. Wewouldliketocreateaconfidenceinterval.Whichofthefollowingwouldproduce
thenarrowestinterval?
a. A99%confidencelevelandasamplesizeof50subjects.
b. A90%confidencelevelandasamplesizeof300subjects.
c. A90%confidencelevelandasamplesizeof50subjects.
d. A99%confidencelevelandasamplesizeof300subjects.
3. Wewouldliketoconstructa95%confidenceintervalforthemeanofapopulation
withsigmaknown.Whatistheappropriateconfidencemultiplier?
a. 1.96
b. 2.33
c. 2.93
d. Itisimpossibletotellwithoutknowingthesamplesize.
Usethefollowingforquestions4‐5:
Dataonheight(ininches)iscollectedforasampleof100adults.Thisdataisusedto
producetwointervals.The99%confidenceintervalforthetrueaverageheightisfrom67
to69inches.The99%predictionintervalisfrom65to71inches.
Forquestions4and5,determineisthestatementisvalidorinvalid.
4. Thepredictionintervaliswiderthantheconfidenceintervalbecausethereismore
variabilitybetweenindividualsthansamplemeans.
a. Valid
b. Invalid
5. With99%confidence,wecaninferthattheintervalof67to69inchesincludesthe
trueaverageheightofadultsinthepopulationrepresentedbythissample.
a. Valid
b. Invalid
6. UsetheconfidenceintervaltotestthehypothesesHo:µ=68vs.Ha:µ≠68.Whatis
yourconclusion?
a. RejectHo,sincethevalueof68isintheconfidenceinterval. b. RejectHo,sincethevalueof68isnotintheconfidenceinterval.
c. FailtorejectHo,sincethevalueof68isintheconfidenceinterval.
d. FailtorejectHo,sincethevalueof68isnotintheconfidenceinterval.
7. Aregressionoftheweight(inpounds)ofacaronitscitygasmileage(inmilesper
gallon)producedthefollowingregressionequationandr‐squaredvalue:
CityMPG=38.907536‐0.0052723642Weight
R‐squared=0.5434522
Whatisthevalueofthecorrelation(r)?
a. r=‐0.005
b. r=0.005
c. r=‐0.737
d. r=0.737
Usethefollowingforquestions8‐10:
BelowisStatCrunchoutputfortheregressionusingheight(ininches)topredictweight(in
pounds)forplayersintheNationalFootballLeague(NFL)forthe2009season.Usethisto
answerquestions5‐8.
Simple linear regression results: Dependent Variable: WT Independent Variable: HT WT = ‐674.2817 + 12.444855 HT R (correlation coefficient) = 0.7763 R‐sq = 0.6026 8. Whatistheexpectedincreaseinweightforeachadditionalinchinheight?
a. 12.44pounds
b. 49.88pounds
c. 70.63pounds
d. 674.2pounds
9. Whatpercentofthevariationinplayer’sweightisexplainedbyitslinear
relationshipwithheight?
a. 12.44%
b. 49.88%
c. 70.63%
d. 674.2%
10. Thiscanbedescribedasafairlystrongrelationshipbecause
a. Thecorrelationiscloserto1than‐1.
b. Thecorrelationiscloserto1than0.
c. Thesquareofthecorrelationiscloserto1than0.
d. Bothbandcbutnota.
Usethefollowingforquestions11‐15:
ScienceDaily) ‐‐ Pecan trees, like many fruit trees, have a tendency to bear fruit in cycles, producing a large crop in one or two years, followed by one or two years with little or no crop. This cycle creates supply and marketing challenges that can have severe negative effects on the pecan industry. To address this issue, researchers at the University of Georgia's Department of Horticulture studied the effects of mechanical fruit thinning on pecan yield using 'Sumner' and 'Cape Fear' pecan trees, two important cultivars prevalent in areas of the southeastern U.S. Ten 20‐year‐old trees of both 'Sumner' and 'Cape Fear' were used for the study. Five trees of each cultivar were mechanically thinned using a tree shaker with a hydraulic shaker head ‐‐ a process called trunk shaking ‐‐ to remove 30% to 40% of the fruit on each tree, and five trees were not thinned. According to the study, yields from thinned and nonthinned 'Sumner' trees were almost identical in 2007, the year of thinning. The OFF year return crop and return crop value of 'Cape Fear' and 'Sumner' was increased by mechanical thinning in the ON year, thus enhancing the total 2‐year value and 2‐year average value of both cultivars. The researchers concluded that increased profitability using mechanical fruit thinning results primarily from higher yields and prices in the OFF year of production, which offset any loss in yield and/or crop value generated by fruit thinning in the ON year. 11. Thisstudyisbestdescribedasa
a. arandomizedblockdesign.
b. arandomizedexperiment.
c. anobservationalstudy.
d. Noneoftheabove.
12. Inthisstudy,theexperimentalunits(subjects)were
a. thepecantrees.
b. theuse(ornot)ofmechanicalthinning.
c. thetypeofpecantree(SumnerorCapeFear).
d. thepecanyield.
13. Inthisstudy,theresponsewas
a. thepecantrees.
b. theuse(ornot)ofmechanicalthinning.
c. thetypeofpecantree(SumnerorCapeFear).
d. thepecanyield.
14. Inthisstudy,theblockswere
a. thepecantrees.
b. theuse(ornot)ofmechanicalthinning.
c. thetypeofpecantree(SumnerorCapeFear).
d. thepecanyield.