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A 786 814 b 788 812 c 775 825 d 785 816 138

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Unformatted text preview: uring the past year. A. [11.06 12.14] B. [11.34 11.86] C. [10.44 12.76] D. [11.15 12.05] E. [3.56 19.64] 144. Unoccupied seats on flights cause airlines to lose revenue. Suppose a large airline wants to estimate its average number of unoccupied seats per flight over the past year. 225 flight records are randomly selected and the number of unoccupied seats is noted with a sample mean of 11.6 seats and a standard deviation of 4.1 seats. How many flights should we select if we wish to estimate µ to within 5 seats and be 95% confident? A. 44 B. 3 C. 2 D. 110 E. 6 1-649 Chapter 01 - An Introduction to Business Statistics Chapter 08 Confidence Intervals Answer Key True / False Questions 1. The t distribution always has n degrees of freedom. FALSE AACSB: Reflective Thinking Bloom's: Knowledge Difficulty: Easy Topic: Confidence interval for population mean σ unknown 2. When the margin of error is added to and subtracted from the sample mean an interval is formed that will contain µ with probability of (1 - α). TRUE AACSB: Reflective Thinking Bloom's: Knowledge Difficulty: Medium Topic: Confidence interval for population mean 3. The standard error of the sample mean is s/√n. TRUE AACSB: Reflective Thinking Bloom's: Knowledge Difficulty: Medium Topic: Confidence interval for population mean 1-650 Chapter 01 - An Introduction to Business Statistics 4. Assuming the same level of significance α, as the sample size increases, the value of tα/2approaches the value of zα/2. TRUE AACSB: Reflective Thinking Bloom's: Knowledge Difficulty: Medium Topic: Confidence interval for population mean σ unknown 5. When constructing a confidence interval for a sample proportion, the t distribution is appropriate if the sample size is small. FALSE AACSB: Reflective Thinking Bloom's: Knowledge Difficulty: Medium Topic: Confidence interval for population proportion 6. First a 90% confidence interval is constructed from a sample size of 100. Then, for the same identical data, a 92% confidence interval is constructed. The width of the 90% interval is wider than the 92% confidence interval. FALSE AACSB: Reflective Thinking Bloom's: Comprehension Difficulty: Medium Topic: Confidence interval 7. When the population is normally distributed and the population standard deviation σ is unknown, then for any sample size n, the sampling distribution of is based on the z distribution. FALSE AACSB: Reflective Thinking Bloom's: Knowledge Difficulty: Medium Topic: Confidence interval for population mean σ unknown 1-651 Chapter 01 - An Introduction to Business Statistics 8. When the sample size and sample standard deviation remain the same, a 99% confidence interval for a population mean, µ will be narrower than the 95% confidence interval for µ. FALSE AACSB: Reflective Thinking Bloom's: Comprehension Difficulty: Medium Topic: Confidence interval for population mean σ unknown 9. When the level of confidence and sample standard deviation remain the same, a confidence interval for a population mean based on a sample of n = 100 will be narrower than a confidence interval for a population mean based on a sample of n = 50. TRUE AACSB: Reflective Thinking Bloom's: Comprehension Difficulty: Medium Topic: Confidence interval for population mean σ unknown 10. When the level of confidence and the sample size remain the same, a confidence interval for a population mean µ will be wider, when the sample standard deviation s is small than when s is large. FALSE AACSB: Reflective Thinking Bloom's: Comprehension Difficulty: Medium Topic: Confidence interval for population mean σ unknown 11. When the level of confidence and sample proportion remain the same, a confidence interval for a population proportion p based on a sample of n = 100 will be wider than a confidence interval for p based on a sample of n = 400. FALSE AACSB: Reflective Thinking Bloom's: Comprehension Difficulty: Medium Topic: Confidence interval for population proportion 1-652 Chapter 01 - An Introduction to Business Statistics 12. When the level of confidence and sample size remain the same, a confidence interval for a population proportion p will be narrower when is larger than when is smaller. FALSE AACSB: Reflective Thinking Bloom's: Comprehension Difficulty: Medium Topic: Confidence interval for population proportion 13. When solving for the sample size needed to compute a 95% confidence interval for a population proportion "p", having a given error bound "B", we choose a value of makes as small as reasonably possible. FALSE that AACSB: Reflective Thinking Bloom's: Comprehension Difficulty: Medium Topic: Sample size determination for population proportion 14. When determining the sample size n, if the value found for n is 79.2, we would choose to sample 79 observations. FALSE AACSB: Reflective Thinking Bloom's: Knowledge Difficulty: Medium Topic: Sample size determination 1-653 Chapter 01 - An Introduction to Business Statistics Multiple Choice Questions 15. The t distribution approaches the _______________ as the sample size ___________. A. Binomial, increases B. Binomial, decreases C. Z, decreases D. Z, increase...
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