# 420Hw01 - STAT 420 Fall 2010 Homework #1 (10 points) (due...

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STAT 420 Fall 2010 Homework #1 (10 points) (due Friday, September 3, by 3:00 p.m.) 1. 3.5 The salary of junior executives in a large retailing firm is normally distributed with standard deviation σ = \$1,500. If a random sample of 25 junior executives yields an average salary of \$16,400, what is the 95-percent confidence interval for μ , the average salary of all junior executives. 2. 3.12 Redo Problem 3.5 without assuming that the population standard deviation is known. You are given s = \$1,575.

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3. A coffee machine is regulated so that the amount of coffee dispensed is normally distributed. A random sample of 17 cups had an average of 7.91 ounces per cup and a sample standard deviation of 0.175 ounces. a) Construct a 90% confidence interval for the overall average amount of coffee dispensed by the machine. b) The coffee machine manufacturer claims that the overall average amount of coffee dispensed is at least 8 ounces. Find the P-value of the test H 0 : μ = 8 vs. H 1 : μ < 8. c)
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## This note was uploaded on 12/17/2010 for the course STAT 420 taught by Professor Stepanov during the Spring '08 term at University of Illinois, Urbana Champaign.

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420Hw01 - STAT 420 Fall 2010 Homework #1 (10 points) (due...

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