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Homework 6 Solutionsb

# Homework 6 Solutionsb - Homework 6 Chapter 9 Problem 4 Your...

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Homework 6 Chapter 9 Problem 4 Your quality control department has just analyzed the contents of 20 randomly selected barrels of materials to be used in manufacturing plastic garden equipment. The results found an average of 41.93 gallons of usable 1material per barrel, with a standard error of 0.040 gallon per barrel. Find the two-sided 95% confidence interval for the population mean. X tS X ± X-bar = 41.93 t-crit at 95% w/ 19 d.f. = 2.093 S x-bar = 0.040 (given) ) 040 . 0 ( ) 093 . 2 ( 93 . 41 × ± The 95% confidence interval extends from 41.85 to 42.01 gallons. Problem 16 The following quotes for cleaning cost have been obtained from a random sample of 12 providers chosen from a much larger population, prior to awarding a contract for these services: \$114, 154, 142, 132, 127, 145, 135, 138, 126, 142, 135, 124 a. Approximately how far is the average of these 12 quotes from the unknown mean for the entire population of providers? X-bar = \$134.50 S = \$10.79 = = = 12 79 . 10 n S S X \$3.115 b. Find the 95% confidence interval for the population mean quote.

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Homework 6 Solutionsb - Homework 6 Chapter 9 Problem 4 Your...

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