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Unformatted text preview: Name: Assigned TF and Section time: Statistics 100 Quiz 4 Wednesday 6 April 2011 There are three problems on the quiz. The third problem is on the back page. Suppose home prices in a city are approximately Normally distributed with a standard deviation of σ = $25 , 000 . A real estate agent takes a random sample of n = 25 homes and finds a sample average price of x = $208 , 000 . 1. (8 points) Calculate a 95% confidence interval for the population average μ home price in the city. ¯ x ± z 1 . 05 / 2 × σ √ n ¶ 208000 ± 1 . 96 × 25000 √ 25 ¶ 208000 ± 9800 (198200 , 217800) We are 95% confident that the population average house price μ is in the interval ($198 , 200 , $217 , 800) . 2. (6 points) Calculate a 90% confidence interval for μ . We can use the same equation as above. The only part that needs to change is the z value. Instead of using z . 975 , we use z . 95 : x ± z 1 . 10 / 2 × σ √ n ¶ 208000 ± 1 . 64 × 25 , 000 √ 25 ¶ 208000 ± 8200 (199800 , 216200) Page 1 of 2 Name:...
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 Spring '11
 Grandal
 Statistics, Null hypothesis, $25, $199, average house price, $198

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