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Unformatted text preview: Econ 310: Problem Set #8 Solutions Andres AradillasLopez 1. Exercise 6.10 (a) The 95% confidence interval is 93 ± 11 = 82 to 104. (The sample size is not needed.) (b) Greater than 11: A wider margin of error is needed in order to be more confident that the interval includes the true mean. 2. Exercise 6.24 (a) To change from hours to minutes, multiply by 60: ¯ x m = 60¯ x h = 906 and σ m = σ h = 300 minutes. (b) For mean time in minutes, the 95% confidence interval is 906 ± (1 . 96)(300 / √ 1200) = 906 ± 16 . 9741 = 889 . 0259 to 922.9741 minutes. (c) This interval can be found by multiplying the previous interval (14.8171 to 15.3829 hours) by 60. 3. Exercise 6.26 (a) The standard deviation of the mean is σ ¯ x = 3 . 5 / √ 20 . = 0 . 7826 mpg. (b) For the mean fuel efficiency, the 95% confidence interval is 43 . 17 ± (1 . 96)(3 . 5 / √ 20) = 43 . 17 ± 1 . 5339 = 41 . 6361 to 44.7039 mpg....
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This note was uploaded on 07/14/2011 for the course ECON 2023 taught by Professor Rush during the Spring '08 term at University of Florida.
 Spring '08
 Rush

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