An article in the National Geographic News ("U.S. Racking Up Huge Sleep Debt." February 24, 2005) argues that Americans are increasingly skimping on their sleep A researcher in a small Midwestern town...

Extracted text: An article in the National Geographic News ("U.S. Racking Up Huge Sleep Debt." February 24, 2005) argues that Americans are increasingly skimping on their sleep A researcher in a small Midwestern town wants to estimate the mean weekday sleep time of its adult residents. He takes a random sample of 80 adult residents and records their weekday mean sleep time as 6.4 hours. Assume that the population standard deviation is fairly stable at 1.8 hours. [You may find it useful to reference the z table.) a. Calculate the 95% confidence interval for the population mean weekday sleep time of all adult residents of this Midwestem town (Round intermediote calculations to at least 4 decimal places. Round "z" volue to 2 decimol places and final answers to 2 decimal places.) Confidence interval to b. Can we conclude with 95% contfidence that the mean sleep time of all adult residents in this midwestern town is not 7 hours? O Yes, since the confidence interval contains the value 7 O Yes, since the confidence interval does not contain the value 7. ONo, since the confidence interval contains the value 7 ONo, since the confidence interval does not contain the value 7.