374 CHAPTER 7 Hypothesis Testing with One Sample In Exercises 19 and 20, use the TI-84 Plus displays to make a decision to reject or fail to reject the null hypothesis at the level of significance. 19. a = 0.05 20. a = 0.01 Graphical Analysis In Exercises 21 and 22, state whether each standardized test statistic z allows you to reject the null hypothesis. Explain your reasoning. 21. (a) z = -1.301 22. (a) z = 1.98 (b) z = 1.203 (b) z = -1.89 (c) z = 1.280 (c) z = 1.65 (d) z = 1.286 (d) z = -1.99 z z0 = 1.285 1 2 3 −1 −2 −3 0 z −z0 = −1.96 z0 = 1.96 1 2 3 −1 −2 −3 0 Finding Critical Values and Rejection Regions In Exercises 23–28, find the critical value(s) and rejection region(s) for the type of z@test with level of significance a. Include a graph with your answer. 23. Left-tailed test, a = 0.03 24. Left-tailed test, a = 0.09 25. Right-tailed test, a = 0.05 26. Right-tailed test, a = 0.08 27. Two-tailed test, a = 0.02 28. Two-tailed test, a = 0.12 In Exercises 29–32, test the claim about the population mean m at the level of significance a. Assume the population is normally distributed. 29. Claim: m = 40; a = 0.05; s = 1.97 Sample statistics: x = 39.2, n = 25 30. Claim: m Ú 1475; a = 0.07; s = 29 Sample statistics: x = 1468, n = 26 31. Claim: m ≠ 5880; a = 0.03; s = 413 Sample statistics: x = 5771, n = 67 32. Claim: m … 22,500; a = 0.01; s = 1200 Sample statistics: x = 23,500, n = 45
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