# 9 the parameter is the population mean h 0 μ 40 h 1

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9. The parameter is the population mean. H 0 : μ = 40, H 1 : μ ≠ 40, Test statistic: z = 2.32, Critical values: −1.96, 1.96, P -value: 0.0204 [Tech: 0.0203]. Reject H 0 . 11. Page SA-37 The parameter is the population proportion. H 0 : p = 0.6, H 1 : p ≠ 0.6, Test statistic: z = 2.72, Critical values: −2.576, 2.576, P -value: 0.0066 [Tech: 0.0065]. Reject H 0 . We conclude that the proportion of families with one or more pets differs from 0.6. 13. H 0 : p = 0.3, H 1 : p > 0.3, Test statistic: z = 2.63, Critical value: 1.645, P -value: 0.0043. Reject H 0 . We conclude that more than 30% of U.S. adults with children have saved money for college.
4/19/2020 Connect Math Plus 13/19 15. H 0 : σ = 0.1, H 1 : σ < 0.1, Test statistic: χ = 4.195, Critical value: 1.239. Do not reject H 0 . There is not enough evidence to conclude that the standard deviation of weights of cookie boxes is less than 0.1. 17. H 0 : μ = 50,000, H 1 : μ ≠ 50,000, Test statistic: z = −1.50, Critical values: −2.576, 2.576, P -value: 0.1336 [Tech: 0.1329]. Do not reject H 0 . There is not enough evidence to conclude that the mean salary of public school teachers in Georgia differs from \$50,000. 19. H 0 : μ = 1, H 1 : μ > 1, Test statistic: t = 2.377, Critical value: 1.943, P -value is between 0.025 and 0.05 [Tech: 0.0275]. Reject H 0 . We conclude that the mean concentration is greater than 1 milligram per cubic meter. Section 9.7 Exercises 1 and 2 are the Check Your Understanding exercises for this section. Answers to these exercises are on page 480 . 3. Type II 5. increase 7. False 9. a. True b. True c. False d. False 11. a. 0.2578 [Tech: 0.2595] b. 0.6406 [Tech: 0.6388] c. 0.0918 [Tech: 0.0924] d. 0.3707 [Tech: 0.3721] 13. a. 0.5319 [Tech: 0.5316]
4/19/2020 Connect Math Plus b. 0.9962 c. 0.2743 [Tech: 0.2735] d. 0.9761 [Tech: 0.9764] 15. 0.5160 17. 0.9582 [Tech: 0.9586] 19. a. 1.645 b. 0.3342 c. 0.8186 [Tech: 0.8197] CHAPTER 9 Quiz 1. 0.035 2. iv
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4/19/2020 Connect Math Plus 15/19 d. True 5. a. No, because the population standard deviation is unknown. b. Yes, because the population is normal. 6. 1.711 7. True 8. a. z = 2.50 b. Yes c. We conclude that more than 85% of people pass their driver’s test. 9. a. Yes, because the P -value is less than 0.05. b. No, because the P -value is greater than 0.01. 10. False 11. Either the P -value or the value of the test statistic should be reported. 12. Yes 13. True 14. Test statistic: χ 2 = 8.444, Critical value: 10.117, reject H 0 . We conclude that the population standard deviation is less than 15. 15. 0.9871 CHAPTER 9 Review Exercises 1. i. 2.
4/19/2020 Connect Math Plus 16/19 a. b. H 0 : μ = 8.62, H 1 : μ < 8.62. Test statistic: t = −0.387, Critical value: −1.714; P -value is between 0.25 and 0.40 [Tech: 0.3511]. Do not reject H 0 . There is not enough evidence to conclude that the mean number of runs in 2013 is less than the mean number of runs in 2012.