8 Chapter Quiz 460 CHAPTER 8 Hypothesis Testing with Two Samples Take this quiz as you would take a quiz in class. After you are done, check your work against the answers given in the back of the book. For each exercise, perform the steps below. (a) Identify the claim and state H0 and Ha. (b) Determine whether the hypothesis test is left-tailed, right-tailed, or two-tailed, and whether to use a z-test or a t-test. Explain your reasoning. (c) Find the critical value(s) and identify the rejection region(s). (d) Find the appropriate standardized test statistic. (e) Decide whether to reject or fail to reject the null hypothesis. (f) Interpret the decision in the context of the original claim. 1. The mean score on a reading assessment test for 49 randomly selected male high school students was 279. Assume the population standard deviation is 41. The mean score on the same test for 50 randomly selected female high school students was 292. Assume the population standard deviation is 39. At a = 0.05, can you support the claim that the mean score on the reading assessment test for male high school students is less than the mean score for female high school students? (Adapted from National Center for Education Statistics) 2. A music teacher claims that the mean scores on a music assessment test for eighth grade students in public and private schools are equal. The mean score for 13 randomly selected public school students is 146 with a standard deviation of 49, and the mean score for 15 randomly selected private school students is 160 with a standard deviation of 42. At a = 0.1, can you reject the teacher’s claim? Assume the populations are normally distributed and the population variances are equal. (Adapted from National Center for Education Statistics) 3. The table shows the credit scores for 12 randomly selected adults who are considered high-risk borrowers before and two years after they attend a personal finance seminar. At a = 0.01, is there enough evidence to support the claim that the personal finance seminar helps adults increase their credit scores? Assume the populations are normally distributed. Adult 1 2 3 4 5 6 Credit score (before seminar) 608 620 610 650 640 680 Credit score (after seminar) 646 692 715 669 725 786 Adult 7 8 9 10 11 12 Credit score (before seminar) 655 602 644 656 632 664 Credit score (after seminar) 700 650 660 650 680 702 4. In a random sample of 1007 U.S. adults in a recent year, 584 approve of the job the Supreme Court is doing. In another random sample of 1022 U.S. adults taken 3 years prior, 501 approve of the job the Supreme Court is doing. At a = 0.05, can you support the claim that the proportion of U.S. adults who approve of the job the Supreme Court is doing is greater than it was 3 years prior? (Adapted from Gallup)
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