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M147finalf05

# M147finalf05 - Page 1 20 Pts Page 2 17 Pts Page 3 15 Pts...

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Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Total 20 Pts 17 Pts 15 Pts 15 Pts 21 Pts 25 Pts 30 Pts 13 Pts 20 Pts 176 Pts MATH 147 FINAL EXAM Fall 2005 December 14, 2005 Name: Section: DIRECTIONS: Show all work. Solutions with no work will receive NO credit. Neatness counts. All necessary tables are provided at the end of the test. Carry out all your calculations to at least two digits to the right of the decimal point. Part I True/False For questions 1 - 10 circle T for true and F for false. (2 points each) 1. T F In an observational study, the effects of treatment may be confounded with the effects of factors that got the subjects into the treatment or control group in the first place. 2. T F In a histogram with a long right tail, the median is more than the average. 3. T F If you perform above average on an exam and you have an even better performance on the next exam, your overall performance on these two tests can be explained by the regression effect. 4. T F Correlation measures association. But association does not necessarily show causation. It may only show that both variables are simultaneously influenced by some third variable. 5. T F The null-hypothesis assumes that an observed difference is due to chance. 6. T F If a correlation coefficient is .9 then 90% of the points are highly correlated. 7. T F In 1990, four passengers were killed by crashes on commuter airlines, compared to 39 killed on scheduled carriers (like United, Delta, and so forth). These data show that if you decide to fly, it is safer to do so on a commuter airline. 8. T F Ecological correlations are based on rates of averages. They tend to overstate the strength of an association. 9. T F Selection bias was one of the reasons for the large error in the Litery Digest Poll of 1936. 10. T F If the correlation coefficient between two variables is zero ( r = 0), then there is no linear association between the variables. Part II Fill in the blank 1

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For questions 11 - 15 complete the sentence by filling in the blank. (2 points for each blank) 11. When a simple random sample of size 151 is obtained from a population of size 1001, then the correction factor is . 12. A box contains three tickets with a 0 and five tickets with a 1. Eighty draws are made at random with replacement. There are 47 1’s among the draws. The chance error is and the SE is . 13. An investigator collects data on hourly wage rates for three groups of workers. Workers in group B earn about twice as much as those in group A; workers in group C earn about \$10 an hour more than those in group A. In the blank indicate which histogram corresponds to Group A: , 14. Two variables have a correlation coefficient of r = 0 . 5. If each of the data items of the first variable are multiplied by 2, the resulting correlation coefficient is .
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M147finalf05 - Page 1 20 Pts Page 2 17 Pts Page 3 15 Pts...

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