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STAT302: Secs 102 & 103Summer I 1998Exam #1Fo r m AInstructor: Julie Hagen Carroll1. Don’t even open this until you are told to do so.2. Be sure to mark your section number (102 or 103) and your test form (A, B, C or D) on the scantron!3. Sign your name where indicated on your scantron and write your Wednesday section number andcomputer number beside it. Also, you must place your scantron in the correct section stack (for nextTuesday).4. There are 20 multiple-choice questions on this exam, each worth 5 points. There is partial credit. Pleasemark your answers clearly on the scantron. Multiple marks will be counted wrong.5. You will have 60 minutes to finish this exam.6. If you are caught cheating or helping someone to cheat on this exam, you both will receive a grade ofzero on the exam. You must work alone.7. This exam is worth 100 points, and will constitute 25% of your final grade.8. Good luck!1STAT302: 102&103 Exam #1, Form A Summer I 19981. What is the approximate correlation coefficient,r, of the data in the scatterplot above?A. strongly negativeB. moderately negativeC. weakD. moderately positiveE. strongly positive2. If the point (2,1) is added to the data above,which of the following will be affected?A. the correlation coefficientB. the interceptC. the slopeD. All of the above will be affected.E. Exactly two of the above will be affected.3. Suppose you get a z-score = 1.2 on this exam.Question #10 is really hard, so I decide to giveeveryone credit, i.e., I give 5 points to everyonewho missed it. What SHOULD you think aboutthis if you got the problem right originally?A. It doesn’t matter since your z-score wouldstay the same.B. You get gypped since your z-score woulddecrease.C. You benefit since your z-score would in-crease.D. Your z-score would increase, but so wouldeveryone else’s.E. Your z-score would decrease, but so wouldeveryone else’s.4. Which of the following is a continuous numericvariable?A. age in yearsB. your exam score out of 100 pointsC. your classificationD. your heightE. exactly two of the abovePercentiles Smallest1% -1.662996 -1.6629965% -1.637709 -1.63770910% -1.604434 -1.60443425% -1.500942 -1.56930250% -1.051385Largest75% -.7622945 -.14041390% .0638196 .063819695% .6425944 .642594499% 1.5275 1.52755. How many outliers are there is the data repre-sented above?A. 0B. 1C. 2D. 3E. 76. What is the shape of the data above?A. skewed right (positively)B. skewed left (negatively)C. impossible to tell without a graphD. uniformE. normal7. If you are given a set of 25 observations and youincrease the maximum ONLY by 15, which ofthe following will be true?A. the mean and the standard deviation willincreaseB. the median and the IQR will increaseC. the IQR but not the median will increaseD. Two of the above will be true.E. None of the above will be true.8. Which of the following is/are true?A. A correlation coefficient = 0 means the leastsquares line is horizontal (flat).B. A correlation coefficient = 0 means that thepoints don’t deviate from the least squaresline.C. A slope = 1 means the correlation coeffi-cient = 1.D. All of the above are true.E. None of the above are true.2STAT302: 102&103 Exam #1, Form A Summer I 19989. Which of the Rules for distributions apply to thedata above?A. Just because this is a normal quantile plotdoesn’t mean the data is normal, so you canonly apply Chebyshev’s Rule.B. The data is approximately normal, so youcan only apply the Empirical Rule.C. Both Rules apply to this data.D. Neither Rule applies to this data.E. The mean and the median must be equalfor the Empirical Rule to apply.10. Suppose your data is approximately normallydistributed with a mean, x = 25 and standarddeviation, sx= 3. What is the approximate 95thpercentile of your data? (Note: the 95th per-centile has 95% of the data is below it.)A. 19B. 22C. 28D. 31E. 3411. Which of the following indicate that the data isskewed left (negatively)?A. The mode (tallest bin) of the histogram ison the right, and the other bins get contin-ually shorter as you go left.B. The boxplot has the median, ˜x,closertoQ3and the maximum than to Q1and theminimum.C. The mean, x, is greater than the median, ˜x.D. All of the above indicate left skewness.E. Exactly two of the above (excluding D.)12. Explain the boxplot for Tru ck.A. There are only 5 observations.B. x =˜xC. Q3= Q1D. Q3=˜x=Q1E. Q3=˜xor ˜x = Q113. Suppose x =5andsx=2. Whatisyand syify =3x−4?A. y =15andsy=6B. y =15andsy=2C. y =11andsy=10D. y =11andsy=2E. y =11andsy=614. For a certain dataset, you are told that the stan-dard deviation, s =0. Whatelsecanyousayabout the dataset?A. the mean, x =0B. the median, ˜x =0C. the IQR = 0D. all of the aboveE. none of the above3STAT302: 102&103 Exam #1, Form A Summer I 199815. What are the approximate mean and median forthe data in the histogram above?A. The mean is about 1 and the median is lessthan 1.B. The mean is less than 1 and the median isabout 1.C. The mean is greater than 1 and the medianis about 1.D. The mean is about 1 and the median isgreater than 1.E. It can’t be determined from a histogram.16. Given a least squares line of ˆy =14−0.3x,whatis the residual for the point (2, 9)?A. -4.4B. -2.3C. 11.3D. 13.4E. 2.317. Suppose you don’t know anything about theshape (distribution) of your dataset. What per-centage of the observations can you say arewithin 1 standard deviation of the mean?A. You can’t say.B. 68%C. 75%D. 89%E. 95%Percentiles Smallest1% -1.889607 -1.8896075% -1.866672 -1.86667210% -1.405686 -1.40568625% -.7113619 -1.1971950% .1811576Largest75% 1.124482 1.54501690% 1.596731 1.59673195% 1.613076 1.61307699% 1.914647 1.91464718. Numbering the boxplots from 1 to 6 starting atthe left, which one corresponds to the outputabove?A. 1B. 2C. 3D. 5E. 619. Which of the boxplots have the mean and themedian approximately equal?A. 1 and 2 only since they’re approximatelynormalB. 1 onlyC. 1, 2 and 3D. 3 onlyE. 1and3only20. Which of the boxplots has an IQR of closest to1?A. 1B. 2C. 3D. 4E. 64STAT302: 102&103 Exam #1, Form A Summer I 1998Answers: 1. B 2. D 3. B 4. D 5. C 6. A7. A 8. A 9. C 10. D 11. E 12. E 13. E14. E 15. B 16. A 17. A 18. C 19. C 20.

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