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t-Test and F Test - Help Session IV: Practice Problems 1....

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Help Session IV: Practice Problems 1. Thirty fast food restaurants including Wendy’s, Mc Donald’s, and Burger King were visited during the summer of 2000 (The Cincinnati Enquirer, July 9,2000). During each visit, the customer went to the drive through and ordered a basic meal such as a “combo” meal or a sandwich, fries, and shake. The time between pulling up the menu board and receiving the filled order was recorded. The time in minutes taken in each of the 30 visits are summarized below. Descriptive Statistics: Time Variable N N* Mean SE Mean StDev Minimum Q1 Median Q3 Maximum Time 30 0 3.800 0.412 2.257 0.900 2.175 3.150 5.050 9.10 a. Provide a point estimate of the population mean drive-through time at fast-food restaurants. b. At 95%, what is the margin of error? c. What is the 95% confidence interval estimate of the population mean? 2. A well-known credit card firm wishes to estimate the proportion of credit card holders who carry a nonzero balance at the end of the month and incur an interest charge. Assume that the desired margin of error is 0.03 at 98% confidence. a. How large a sample should be selected if it is anticipated that roughly 70% of the firm’s card holders carry a nonzero balance at the end of the month? b. How large a sample should be selected if no planning value for the proportion could be specified? c. How large (conservatively) a sample should be selected if it is anticipated that between 60 to 80 percent of the firm’s card holders carry a nonzero balance at the end of the month?
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3. Playbill is a magazine distributed around the country to people attending musicals and other theatrical productions. The mean annual household income for the population of Playbill readers is $119,155 (Playbill, January 2006). Assume the standard deviation is 20700. A San Francisco civic group has asserted that the mean income for the theater goers in the Bay Area is higher. A sample of 60 theater attendees in the Bay Area showed that a sample household income of $126,100. a. Develop hypotheses that can be used to determine whether the sample data support the conclusion that the theater attendees in the Bay Area have a higher mean household income than that for all Playbill readers. b. What is the p-value based on the sample of 60 theater attendees in the Bay Area?
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t-Test and F Test - Help Session IV: Practice Problems 1....

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