This document provides a list of 21 practice questions for a MATH 221 Week 7 Quiz. The questions cover topics related to normal distributions, z-scores, probabilities, sampling distributions, confidence intervals, and estimating proportions. They involve calculating probabilities, finding z-scores, determining sample sizes needed for confidence intervals, and interpreting results. The document aims to help students prepare for an exam on statistical concepts taught in MATH 221 during the 7th week of the course.

1. DeVry-University MATH 221 Week 7 Quiz
Get help DeVry-University MATH221 Week7 Quiz. We provide assignment, homework, discussions
and case studies help for all subjects DeVry-University for Session 2015-2016.
MATH 221 Week 7 Quiz
1. In a normal distribution,whichisgreater,the meanorthe median?Explain.
2. The systolicbloodpressuresof asample of adultsare normallydistributed,withamean
pressure of 115 millimetresof mercuryandstandarddeviationof 3.6millimetresof mercury.The
systolicbloodpressure of fouradultsselectedatrandomare 122 millimetres‘of mercury,114
millimetresof mercury,107 millimetresof mercury,and126 millimetresof mercury,the graphof the
standardnormal distributionisshowntothe right. Complete parts(a) through(c) below.
3. For the standardnormal distributionshownonthe right,findthe probabilityof zoccurringin
the indicatedregion.
4. Findthe indicatedprobabilityusingthe standardnormal distribution.
5. Assume amemberis selectedatrandomfromthe populationrepresentedbythe graph.findthe
probabilitythatthe memberselectedatrandomisfrom the shadedareaof the graph . Assume the
variable x isnormallydistributed.
6. In a recentyear,scoreson a standardizedtestforhighschool witha 3.50 to 4.00 grade point
average were normallydistributed,withameanof 39.7 and a standarddeviationof 1.7.a studentwitha
3.50 to 4.00 grade pointaverage whotookthe standardizedtestisrandomlyselected.
7. Use the normal distributionof fishlengthsforwhichthe meanis10 inchesandthe standard
deviationis2inches.Assume the variablex isnormallydistributed.
8. Use the normal distributionof fishlengthsforwhichthe meanis10 inchesandthe standard
deviation 2inches.Assume the variable x isnormallydistributed.
9. Findthe indicatedz-score showninthe graphto the right.

2. 10. Findthe z-score that has85.1% of the distribution’sareatoitsright.
11. The time spent(indays) waitingfora heart transplantintwo statesforpatientswithtype A+
bloodcan be approximatedbyanormal distribution,asshowninthe graphto the right.
12. Use the central limittheoremtofindthe meanandstandarderror of the meanof sampling
distribution.Thensketchagraph of the samplingdistribution.
13. Findthe probabilityandinterpretthe results.if convenient,use technologytofindprobability.
Duringa certainweekthe meanprice of gasoline was$2.702 pergallon.A randomsample of 34 gas
stationsisdrawnfrom thispopulation.Whatisthe probabilitythatthe meanprice forthe sample was
between$2.694 and $ 2.716 thatweek?Assume mean=$0.05.
14. Findthe marginof errorfor the givenvaluesof C,S,andN.
15. You are giventhe sample meanandthe sample standarddeviation.Use thisinformationto
construct the 90% and 95% confidence intervalsforthe populationmean.Interpretthe resultsand
compare the widthsof the confidence intervals.If convenient,use technologytoconstructthe
confidence intervals.
16. A doctor wantsto estimate the HDLcholesterol of all 20 to 29 yearold females.How many
subjectsare neededtoestimate the HDLcholesterol within4pointswith99% confidence assuming
mean=18.1? Suppose the doctorwouldbe contentwith90% confidence.How doesdecreasein
confidence affectthe sample size required?
17. Findthe critical value tc forthe confidence level c=0.80 and sample size n=13.
18. Findthe marginof errorfor the givenvaluesof c,s, and n.
19. The monthlyincomesfor12 randomlyselectedpeople,eachwithabachelor’sdegree in
economics,are shownonthe right.
20. In a surveyof 3327 adults,1475 saytheyhave startedpayingbillsonlineinlastyear?
21. A researcherwishestoestimate,with95% confidence,the proportion of adultswhohave within
1% of the true proportion.
http://www.justquestionanswer.com/viewanswer_detail/MATH-221-Week-7-Quiz-1-In-a-normal-
distribution-which-i-36449