Test 2 Version 1 Fall 2010

# Test 2 Version 1 Fall 2010 - QUESTIONS 1-4 An online...

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Unformatted text preview: QUESTIONS 1-4 : An online retailer was interested in the percentage of customers who use expedited shipping during the month of December. A sample of randomly chosen orders during December 2009 showed a 95% confidence interval for the proportion of orders using expedited shipping is 34% ± 4%. 1. What is the meaning of this confidence interval? e A. 95% of the time, the percentage of orders using expedited shipping is 34%. B. 95% of random samples will show that 30% to 38% of orders use expedited shipping. C. The company is 95% confident their sample statistic falls between 30% and 38%. D. 95% of the time, between 30% and 38% of orders use expedited shipping. E. The company is 95% confident the proportion of orders that use expedited shipping is between 30% and 38%. 2. What does the 34% represent? b A. Population parameter B. Sample statistic C. Margin of error D. Probability of an individual order using expedited shipping E. Probability of 95% of orders using expedited shipping 3. Suppose the company increased their sample size, keeping everything else constant. What would be the effect of this change? A. Decrease the margin of error B. Increase the margin of error C. Increase the confidence level D. Higher probability of capturing the sample statistic E. Higher probability of capturing the true proportion of orders that use expedited shipping 4. The shipping manager proposed the use of a 99% confidence interval instead of 95%, which led to an intense debate. Which of the following arguments could be used to defend the use of a 95% confidence interval rather than a 99% confidence interval? A. A bigger sample size is required to construct a 99% confidence interval B. A 95% confidence interval has a higher probability of being correct C. A 95% confidence has a smaller margin of error. D. A 95% confidence interval is easier to construct. E. A 99% confidence interval would be more expensive than a 95% confidence interval. _____________________________________________________________________________ __ QUESTIONS 5-9 : In 2008 Gallup conducted a poll of 120 Columbian residents to estimate the percentage of Columbians who favored a free trade agreement with the USA. 5. Suppose the true proportion of Columbians favoring a free trade agreement is 0.60. What is the probability the survey will find 66 or fewer Columbian residents who favor a free trade agreement? A. 0.1314 B. 0.1357 C. 0.5500 D. 0.8643 E. 0.8686 6. Suppose you didn’t know the true proportion was 0.60. The poll found 63 Columbians favored a free trade agreement with the USA. Construct a 99% confidence interval for the proportion of Columbians who favor a free trade agreement with the US: A. (0.479, 0.571) B. (0.450, 0.600) C. (0.436, 0.614) D. (0.562, 0.718) E. (0.408, 0.642) 7. The political opposition leader claims that there should not be a free trade agreement with the USA, since less than 50% of Columbians support it. With 99% confidence, what can we conclude on the basis of the above survey results (63 Columbians in favor)?conclude on the basis of the above survey results (63 Columbians in favor)?...
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Test 2 Version 1 Fall 2010 - QUESTIONS 1-4 An online...

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