1.Number of JobsA sociologist found that in a sample of55

retired men, the average number of jobs they had during their lifetimes was7.2

. The population standard deviation is2.1.

(b) Find the99%confidence interval of the mean number of jobs. Round intermediate and final answers to one decimal place.

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2.Freshmen GPAsFirst-semester GPAs for a random selection of freshmen at a large university are shown. Estimate the true mean GPA of the freshman class with 90% confidence. Assume =0.62. Round intermediate and final answers to two decimal places. Assume the population is normally distributed.

1.9, 2.0,2.7,3.8,3.0,2.8,3.3,2.7,2.9,2.0,3.2,1.9,2.8,2.2,4.0,1.9,2.8,2.0,2.7,3.9

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3.Work Time Lost due to AccidentsAt a large company, the Director of Research found that the average work time lost by employees due to accidents was 95 hours per year. She used a random sample of 23 employees. The standard deviation of the sample was 5.3 hours. Estimate the population mean for the number of hours lost due to accidents for the company, using a 99% confidence interval. Assume the variable is normally distributed. Round intermediate answers to at least three decimal places.Round your final answers to the nearest whole number.

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4.Social Networking SitesA recent survey of6social networking sites has a mean of7.73million visitors for a specificmonth.The standard deviation was4million.Find the90%confidence interval of the truemean.Assume the variable is normallydistributed.Round your answers to at least two decimalplaces.

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5.Educational TelevisionIn a random sample of210people,150said that they watched educational television. Find the90% confidence interval of the true proportion of people who watched educational television. Round intermediate answers to at least five decimal places. Round your final answers to at least three decimal places.

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6.Wi-Fi AccessA survey of43students in grades4 through12found64%have classroom Wi-Fi access. Find the95%

confidence interval of the population proportion. Round all intermediate and final answers to at least three decimal places.

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