hw3sol-book (1)

# hw3sol-book (1) - confidence interval even though the level...

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Solution for hw3 (textbook problems) 8-6 a) Sample mean from the first confidence interval =37.53 + (49.87-37.53)/2 = 43.7 Sample mean from the second confidence interval =35.59 + (51.81-35.59)/2 = 43.7 b) The 99% CI is (35.59, 51.81) and the 95% CI is (37.53, 49.87). The higher the confidence level, the wider the CI. 8-11 95% Two-sided CI on the true mean yield: where f8e5 x = 90.480, σ = 3 , n=5 and z 0.025 = 1.96 8-14 a) 95% Two-sided CI on the true mean life of a 75-watt light bulb For α = 0.05, z α /2 = z 0.025 = 1.96 , and f8e5 x = 1014, σ =25 , n=20 b) 95% One-sided CI on the true mean piston ring diameter For α = 0.05, z α = z 0.05 =1.65 and f8e5 x = 1014, σ =25 , n=20 The lower bound of the one sided confidence interval is lower than the lower bound of the two-sided

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Unformatted text preview: confidence interval even though the level of significance is the same. This is because all of the Type I probability (or α29 is in the left tail (or in the lower bound). 8-27 95% confidence interval on mean tire life 8-28 99% lower confidence bound on mean Izod impact strength 8-46 95% two sided confidence interval for σ and 8-55 a) 95% confidence interval for the proportion of college graduates in Ohio that voted for George Bush. b) 95% lower confidence bound on the proportion of college graduates in Ohio that voted for George Bush. 8-58 a) 95% Confidence Interval on the true proportion of helmets showing damage b) c)...
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hw3sol-book (1) - confidence interval even though the level...

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