39. Wind power. Should you generate electricity with your own personal wind turbine? That depends on whether you have enough wind on your site. To produce enough energy, your site should have an annual average wind speed of at least 8 miles per hour, according to the Wind Energy Association. One candidate site was monitored for a year, with wind speeds recorded every 6 hours. A total of 1114 readings of wind speed averaged 8.019 mph with a standard deviation of 3.813 mph. You’ve been asked to make a statistical report to help the landowner decide whether to place a wind turbine at this site.

a) Discuss the assumptions and conditions for using Student’s t inference methods with these data. Here are some plots that may help you decide whether the methods can be used:

b) What would you tell the landowner about whether this site is suitable for a small wind turbine? Explain 40. Real estate crash? After the sub-prime crisis of late 2007, real estate prices fell almost everywhere in the U.S.
In 2006–2007 before the crisis, the average selling price of homes in a region in upstate New York was $191,300. A real estate agency wants to know how much the prices have fallen since then. They collect a sample of 1231 homes in the region and find the average asking price to be $178,613.50 with a standard deviation of $92,701.56. You have been retained by the real estate agency to report on the current situation.

a) Discuss the assumptions and conditions for using t-methods for inference with these data. Here are some plots that may help you decide what to do.

b) What would you report to the real estate agency about the current situation?

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Wind Speed (mph) 20 + 15 10 10 5 + # of Readings 150 100 50 0 5 10 Wind Speed (mph) 15 20 250 500 Time 750 1000