Gallup Organization

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Problem 7.30 On February 8, 2002, the Gallup Organization released the results of a poll concerning American attitudes toward the 19th Winter Olympic Games in Salt Lake City, Utah. The poll results were based on telephone interviews with a randomly selected national sample of 1,011 adults, 18 years and older, conducted February 4-6, 2002. a. Suppose we wish to use the poll’s results to justify the claim that more than 30 percent of Americans (18 years or older) say that figure skating is their favorite Winter Olympic event. The poll actually found that 32 percent of respondents reported that figure skating was their favorite event. If, for the sake of argument, we assume that 30 percent of Americans (18 years or older) say figure skating…show more content…
Using the 99 percent confidence interval, can the bank manager be 99 percent confident that mew is less than six minutes? Explain. d. Based on your answers to parts b and c, how convinced are you that the new mean waiting time is less than six minutes? (a) (i) 95% CIn = 100 x-bar = 5.46 s = 2.47 % = 95 Standard Error, SE = σ/√n = 0.2470 z- score = 1.9600 Width of the confidence interval = z * SE = 0.4841 Lower Limit of the confidence interval = x-bar - width = 4.9759Upper Limit of the confidence interval = x-bar + width = 5.9441The confidence interval is [ 4.976 5.944](ii) 99% CIn = 100 x-bar = 5.46 s = 2.47 % = 99 Standard Error, SE = σ/√n = 0.2470 z- score = 2.5758 Width of the confidence interval = z * SE = 0.6362 Lower Limit of the confidence interval = x-bar - width = 4.8238Upper Limit of the confidence interval = x-bar + width = 6.0962The confidence interval is [ 4.824 6.096](b) Yes, the entire 95% CI is less than 6. The manager can be 95% confident that μ is less than 6 minutes.(c) No, a small part of the 99% CI is greater than 6. The manager can’t be 99% confident that μ is less than 6 minutes.(d) At α = 0.05, we are convinced that the mean waiting time is less than 6 minutes, but not at α = 0.01.…show more content…
February 2005, reports on the results achieved by Bank of America in improving customer satisfaction and customer loyalty by listening to the ‘voice of the customer.’ A key measure of customer satisfaction is the response on a scale from 1 to 10 to the question: “Considering all the business you do with Bank of America, what is your overall satisfaction with Bank of America?” Suppose that a random sample of 350 current customers results in 195 customers with a response of 9 or 10 representing “customer delight.” Find a 95 percent confidence interval for the true proportion of all current Bank of America customers who would respond with a 9 or 10. Are we 95 percent confident that this proportion exceeds .48, the historical proportion of customer delight for Bank of

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