APStats 2.1-2.2 Quiz Answers

AP Statistics
Quiz2.lA
Name:
a midwesternelementaryschooltook a "self-concept"testthat
themselves.Higherscoresindicatemorepositiveself-concepts.A
histogramand somesurnmarystatisticsfrom Minitab for thesestudents'self-conceptscoresaregiven
below.
of 78 third-gade
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DescriptiveStatistics: SelfConcept
Variable
SelfConc
N
78
Variable
SelfConc
Minimum
Maximum
20.00
80.00
Median
59.50
TrMean
57.81
Q1
51.00
Q3
65.25
iltp"i--..
SE Mean
1.41
1. Draw an appropriatedensitycurvefor summarizingthe histogramon the graphabove. How would
you describethe shapeof this densitycurve?
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2. Onestudentin the grouphad a self-conceptscoreof 62. Thirty-four studentshad self-concept
scoreshigherthan 62. Describethe locationof this valuewithin the distributionusingraw data,
percentiles,andstandardizedvalues(z-scores).
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Whatis a "typical" self-conceptscorefor a third-graderin this group? Justify your answer.
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Chapter2
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Quiz2.lA
Quiz2.2A
AP Statistics
Name:
1. A studyof elite distancenulnersfound a meanbody weight of 63.1 kilograms(kg), with a standard
deviationof 4.8 kg.
(a) Assumingthat the distribution of weightsis Normal,makean accuratesketchof the weight
distibution with the horizontalaxis markedin kilograms.
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(b) Usethe 68-95-99.7rule to find theproportionof nrnnerswhosebody weightis between48.7
and67.9kg. Showyour method.
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(c) Calculateandinterpretthe 45th percentileof the runners'body weight distribution.
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2. UseTableA to find the proportionof observationsfrom a standardNormal distributionthat
satisfies-1.51 < Z < 0.84. SketchtheNormalcurveandshadethe areaunderthe curvethat is the
answerto the question.
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Give anexampleof a quantitativevariablethatdoesnothavea Normaldishibution. Justiff your
answer.
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Chapter2
Quiz2.2A