STAT303 Secs 506–508Fall 1999Exam #3Instructor: Julie Hagen Carroll1. Don’t EVEN open this until you are told to do so.2. 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.3. You will have 60 minutes to finish this exam.4. 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.5. This exam is worth 100 points, and will constitute 20% of your final grade.6. Good luck!7. Be sure to mark your section number, test form and PRINT the section and computer number forThursday’s class in the space beside where you sign your name. Also, PRINT your name at the top ofthis exam and include your Thursday section and computer number. You will get your scantron andexam back.1STAT303 506–508 Exam #3 Fall 19991. Which of the following is true?A. The t curve is always centered at zero.B. The z curve is used instead of the t curveto be more conservative.C. The t curve is used when we must estimatethe mean.D. All of the above are true.E. Exactly two of the above are true.2. What hypotheses are being tested in the graphabove?A. H0: µ =0vs. HA: µ 6=0B. H0: µ1=14vs. HA: µ2=16.4C. H0: µ1=0vs. HA: µ2=0D. H0: µ1= µ2vs. HA: µ16= µ2E. H0: µ1− µ2=0.077 vs. HA: µ1− µ26=0.07790% |Lower Limit = 10.177573|Upper Limit = 11.82242795% |Lower Limit = 10.020018|Upper Limit = 11.97998299% |Lower Limit = 9.7120853|Upper Limit = 12.2879153. Given the confidence intervals above, what is thecorrect range of the p-value for testing H0: µ =10.2vs.HA: µ 6=10.2?A. p-value > 0.10B. 0.10 >p-value > 0.05C. 0.05 >p-value > 0.01D. p-value< 0.01E. You need a test statistic value to determinethe p-value4. What would happen to the confidence intervalsin the previous problem if we had use a largersample size?A. Each of the confidence intervals would benarrower.B. Each of the confidence intervals would becloser to the width of the z interval for thesame level, asssuming these are t intervals.C. Each of the confidence intervals would bemore likely to include the hypothesizedvalue, 10.2.D. All of the above are true.E. Exactly two of the above are true.5. What would be the consequence of a Type IIerror for the test, H0: µ =10.2vs. HA: µ 6=10.2?A. We would fail to conclude that the truemean was 10.2 when is actually was 10.2.B. We would fail to conclude that the truemean was not 10.2 even though is actuallywas not 10.2.C. We would conclude that the true mean was10.2 when is actually was 10.2.D. We would conclude that the true mean wasnot 10.2 when is actually was 10.2.E. We could fail to conclude that the truemean was 10.2 even though is actually wasnot 10.2.6. What is the advantage of using a paired t-test(Case 10) over either 2 sample t-tests (Cases 8or 9)?A. You only need half as many observations(smaller sample size).B. You have more power (easier to detect adifference).C. You have more degrees of freedom (less con-servative test).D. All of the above are advantages to thepaired t-test.E. Exactly two of the above are advantages tothe paired t-test.2STAT303 506–508 Exam #3 Fall 19997. What is the best explanation of the p-value forthe test above?A. 4.2% of the time we will get a true H0.B. 4.2% of the time we will get 0.42 and 0.59for the sample proportions.C. 4.2% of the time we will get differences of0 when the true proportions are 0.42 and0.59.D. 4.2% of the time we will get differences of0.42 and 0.59 when the true proportons are0.E. 4.2% of the time we will get differences atleast as large as 0.42 − 0.59 when the truedifference is 0.8. Why would you prefer to run a one-sided testsof hypotheses instead of a two-sided?A. If you only cared about whether you werebetter (bigger or smaller, whichever wouldbe appropriate), then the one-sided testwould give you more power.B. If you had a sample mean that was less thanwhat you were testing against, you shouldrun a left-sided test.C. If you knew that the null hypothesis wastrue, you could still get a rejection with aone-sided test.D. You will always get a rejection with a one-sided test if you rejected with a two-sidedtest.E. The one-sided test requires less data to geta rejection.9. If we have created 90, 95 and 99% confidenceintervals using the data above, which intervalswould have contained the hypothesized propor-tion, π =0.5?A. all threeB. only the 90%C. only the 99%D. both the 90 and 95%E. both the 95 and 99%10. A 95% confidence interval for the true mean testscore on this exam is (68.95, 81.05). Which ofthe following is true?A. The sample mean test score is 75.B. You have a 95% chance of making betweena 69 and 81.C. 95% of the class will make between a 69 andan 81.D. 95% of all the different classes will have anaverage between 68.95 and 81.05.E. Exactly two of the above are true.11. Suppose we run a hypothesis test at the 5% sig-nificance level. Which of the following is true?A. If we repeatedly sampled the data and ranthe same test, we will reject about 5% ofthe time.B. If we repeatedly sampled the data and ranthe same test, we will fail to reject about95% of the time.C. If we repeatedly sampled the data and ranthe same test, we will make a Type II errorabout 95% of the time.D. If we repeatedly sampled the data and ranthe same test, we will make a Type I errorabout 5% of the time.E. Exactly two of the above are true.3STAT303 506–508 Exam #3 Fall 199912. In the test above, what would happened if wehad gotten a sample mean,x =60.5, instead?A. We would have tested different hypothesessince we had different data.B. We would have used a different α-level sinceour data was closer to the hypothesizedvalue, 60.C. We would have gotten a different p-valuesince we had different data.D. All of the above are true.E. Exactly two of the above are true.13. Suppose you are interested in the caloric con-tent of hamburgers. You took a random samplefrom 3 different chains and calculated the follow-ing confidence intervals: Chain 1: (248.9,307.8);Chain 2: (263.5,309.3); Chain 3: (307.1,349.7).Which of the following would be the most appro-priate conclusion?A. The true mean caloric content for Chain 3is more than that of Chain 1 or 2.B. The true mean caloric content for Chain 3is more than that of Chain 1 but not Chain2.C. The true mean caloric content is differentfor all three chains.D. The true mean caloric content is possiblythe same for all three
View Full Document
Unlocking...