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Texas Tech University *

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2400

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Statistics

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May 2, 2024

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pdf

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Uploaded by BrigadierFangHare38 on coursehero.com

John works as a “sanitation engineer” for a zoo that has only 7 elephants and 12 zebras in the whole zoo (a budgetary problem). Every day he goes to work he feels like he is shoveling a great deal of waste and he wants to know if the amount of waste that he disposes of on average is different than the normal amount elephant/zebra zoos dispose of. On any given day 1200 pounds of waste, are removed from these types of facilities across the country, however a sample of 19 days found that John shoveled 1600 pounds of waste a day with a standard deviation of 500. Is John shoveling significantly more crap than the average facility, use alpha = .10? 12. What kind of test should you conduct? A. one-sample z-test B. one sample t-test C. dependent samples t-test D. independent samples t-test 13. What is/are the critical values (i.e. cutoff threshold) for this test? A. 1.33 B. 1.77 C. – 1.33, +1.33 D. -1.77, +1.77 14. What is the test statistic? A. 0.8 B. -0.8 C. 3.49 D. -3.49 15. What should you decide? A. Retain the null hypothesis B. Reject the null hypothesis C. Prove the null hypothesis D. Prove the research hypothesis 16. What can you conclude based on this test? Select the BEST answer. A. The amount of crap that John shovels is significantly less than the average sanitation engineer B. The amount of crap that John shovels is significantly greater than the average sanitation engineer C. The amount of crap that John shovels is not significantly different from the average sanitation engineer D. The amount of crap that John shovels is significantly different from the average sanitation engineer Use the following scenario to answer questions 21-25 Susan is interested in determining whether the life of a newly invented cell phone battery is worse than other batteries. Based on a sample of 4 new batteries, Susan believes the new battery lasts 9 hours. The

average battery life for most cell phone batteries is 12 hours with a standard deviation of 3 hours (alpha = .05). 17. What kind of test should you conduct? A. one-sample z-test B. one sample t-test C. dependent samples t-test D. independent samples t-test 18. What is/are the critical values (i.e. cutoff threshold) for this test? A. 0.13 B. -0.13 C. 1.65 D. -1.65 19. What is the test statistic? A. 1 B. -1 C. 2 D. -2 20. What should you decide? A. Retain the null hypothesis B. Reject the null hypothesis C. Prove the null hypothesis D. Prove the research hypothesis 21. What can you conclude based on this test? Select the BEST answer. A. The new battery’s life is significantly shorter than the battery life of average batteries B. The new battery’s life is significantly greater than the battery life of average batteries C. The new battery’s life is significantly different from the battery life of average batteries D. The new battery’s life is not significantly different from the battery life of average batteries Use the following scenario to answer questions 26-30 A researcher believes that pilots’ reaction times are slower when they are tired than when they are well rested. To explore this possibility, she recruits 26 pilots. She tests each pilot’s reaction time at the start of their shift when they are well rested (Mean = 300 milliseconds (ms), SD = 70 ms). Then she tests each pilot’s reaction time again at the end of the shift when pilot’s are less well rested (Mean = 450 ms, SD = 70 ms). She finds that the mean difference is -125 ms (S D = 95 ms). Alpha = .05. 22. What kind of test should you conduct? A. one-sample z-test B. one sample t-test C. dependent samples t-test D. independent samples t-test

23. What is/are the critical values (i.e. cutoff threshold) for this test? A. +1.78 B. -1.78, +1.78 C. -1.71 D. -1.71, +1.71 24. What is the test statistic? A. -1.32, +1.32 B. -1.32 C. -6.71, + 6.71 D. -6.71 25. What should you decide? A. Retain the null hypothesis B. Reject the null hypothesis C. Prove the null hypothesis D. Prove the research hypothesis 26. What can you conclude based on this test? Select the BEST answer. A. Pilots’ reaction times are significantly slower when they are tired than when well rested B. Pilots’ reaction times are significantly faster when they are tired than when well rested C. Pilots’ reaction times are significantly different when they are tired than when wel l rested D. Pilots’ reaction times are not significantly different when they are tired than when well rested Use the following scenario to answer questions 31-37 A sociologist wants to know if children raised in urban areas have different hearing abilities than children raised in rural settings. The sociologist samples of 20 urban children and 24 rural children and measures their hearing ability (higher score = higher ability). Here are the statistics from the study Urban Mean (M 1 ) = 91; Rural Mean (M 2 ) = 93; Urban SD = 4; Rural SD = 5. Assuming α = .05, answer the following questions to address the sociologist’s research question. 27. What kind of test should you conduct? A. one-sample z-test B. one sample t-test C. dependent samples t-test D. independent samples t-test 28. What is/are the critical values (i.e. cutoff threshold) for this test? A. 1.68 B. -1.68, +1.68 C. 2.02 D. – 2.02, +2.02

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