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Unformatted text preview: 1 CHAPTER 12 SECTION 2: INFERENCE ABOUT A POPULATION MULTIPLE CHOICE 50. A random sample of 25 observations is selected from a normally distributed population. The sample variance is 10. In the 95% confidence interval for the population variance, the upper limit is: a. 17.110 b. 6.097 c. 17.331 d. 19.353 ANS: D PTS: 1 REF: SECTION 12.2 51. In a hypothesis test for the population variance, the hypotheses are H : 2 = 30 vs. H 1 : 2 < 30. If the sample size is 20 and the test is being carried out at the 5% level of significance, the null hypothesis is rejected if: a. 2 < 30.144. b. 2 > 10.851. c. 2 < 10.117. d. 2 > 31.410. ANS: C PTS: 1 REF: SECTION 12.2 52. In a hypothesis test for the population variance, the hypotheses are H : 2 = 100 vs. H 1 : 2 100. If the sample size is 15 and the test is being carried out at the 10% level of significance, the rejection region is: a. 2 < 6.571 or 2 > 23.685. b. 2 < 7.790 or 2 > 21.064. c. 2 < 8.547 or 2 > 22.307. d. 2 < 7.261 or 2 < 24.996. ANS: A PTS: 1 REF: SECTION 12.2 53. The statistic ( n- 1) s 2 / 2 has a chi-squared distribution with n - 1 degrees of freedom if: a. the population is normally distributed with variance equal to 2 . b. the sample is normally distributed with variance equal to s 2 . c. the sample has a Student t-distribution with degrees of freedom equal to n - 1. d. All of these choices are true. ANS: A PTS: 1 REF: SECTION 12.2 54. Which of the following is not an example illustrating the use of variance? a. As a measure of risk. b. As a judge of consistency. c. To search for and reduce variability in a process. d. All of these choices are true. ANS: D PTS: 1 REF: SECTION 12.2 2 55. Which of the following conditions is needed regarding the chi-squared test statistic for the test of variance? a. The population random variable must be normal. b. The test statistic must be a non-negative number....
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- Spring '10