Statistics: Z-test: Testing hypotheses – #161


Question: A national organization has been working with utilities throughout the nation to find sites for large wind machines for generating electric power. Wind speeds must average more than 15 miles per hour (mph) for a site to be acceptable. Recently, the organization conducted tests at a particular site under construction for a wind machine. Based on a sample of n = 50 wind speed recordings (taken a random intervals) at the site, the wind speeds averaged x-bar = 14.3 mph, with a standard deviation of s = 4.5 mph. To determine whether the site meets the organization’s requirements, consider the test, Ho: µ = 15 vs. Ha: µ > 15, where µ is the true mean wind speed at the site and α = .01. Calculate the value of the test statistic.

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