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Unformatted text preview: 1 CHAPTER 12 SECTION 3: INFERENCE ABOUT A POPULATION MULTIPLE CHOICE 80. Under what condition(s) does the test statistic for p have an approximate normal distribution? a. When np > 5. b. When np and np (1 - p ) are both > 5. c. When n > 30. d. When np and n (1 - p ) are both > 5. ANS: D PTS: 1 REF: SECTION 12.3 81. In selecting the sample size to estimate the population proportion p , if we have no knowledge of even the approximate values of the sample proportion p 8 , we: a. take another sample and estimate p 8 . b. take two more samples and find the average of their p 8 . c. let p 8 = 0.50. d. let p 8 = 0.95. ANS: C PTS: 1 REF: SECTION 12.3 82. The use of the standard normal distribution for constructing confidence interval estimate for the population proportion p requires: a. np 8 and n (1 - p 8 ) both greater than 5. b. np and n (1 - p ) both greater than 5. c. n (1 + p 8 ) and n (1 - p 8 ) both greater than 5. d. sample size greater than 5. ANS: A PTS: 1 REF: SECTION 12.3 83. Assuming that all necessary conditions are met, what needs to be changed in the formula p 8 t p 8 (1- p 8 ) / n so that we can use it to construct a (1 - ) confidence interval estimate for the population proportion p ? a. p 8 should be replaced by p . b. t should be replaced by z . c. t should be replaced by t / 2 . d. t should be replaced by z / 2 . ANS: D PTS: 1 REF: SECTION 12.3 84. From a sample of 400 items, 14 are found to be defective. The point estimate of the population proportion defective will be: a. 14 b. 0.035 c. 28.57 d. 0.05 ANS: B PTS: 1 REF: SECTION 12.3 2 85. After calculating the sample size needed to estimate a population proportion to within 0.04, your statistics professor told you the maximum allowable error must be reduced to just .01. If the original calculation led to a sample size of 800, the sample size will now have to be: a. 800 b. 3200 c. 12,800 d. 6400 ANS: C PTS: 1 REF: SECTION 12.3 86. The width of a confidence interval estimate for a proportion will be: a. narrower for 99% confidence than for 95% confidence. b. wider for a sample size of 100 than for a sample size of 50. c. narrower for 90% confidence than for 95% confidence. d. narrower when the sample proportion if 0.50 than when the sample proportion is 0.20. ANS: C PTS: 1 REF: SECTION 12.3 87. When determining the sample size needed for a proportion for a given level of confidence and sampling error, the closer to 0.50 that p is estimated to be: a. the smaller the sample size required. b. the larger the sample size required. c. the sample size is not affected. d. the effect cannot be determined from the information given. ANS: B PTS: 1 REF: SECTION 12.3 88. Which of the following would be an appropriate null hypothesis?...
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