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Course Documents

Chapter 1 - Intro

Chapter 2 - Methods for Describing Sets of Data

Chapter 3 - Probability

Chapter 4 - Discrete Random Variables

Chapter 5 - Normal Random Variables

Chapter 6 - Sampling Distributions

Chapter 7 - Confidence Intervals

Chapter 8 - Tests of Hypothesis: One Sample

Chapter 9 - Confidence Intervals and Hypothesis Tests: Two Samples

Sample Exam I: Chapters 1 & 2

Sample Exam II: Chapters 3 & 4

Sample Exam III: Chapters 5 & 6

Sample Exam IV: Chapters 7 & 8

Problem 2

9.11 Hypothesis Test to Compare Two Population Variances: Independent Sampling

Variation and Quality: A sign of quality is low variation in the dimensions of key manufactured components for a product.  For example, a study looked at 25 shelves that were designed for a bookcase sold at the retail chain Wal-mart.  This bookcase needed to be put together by the customer.  They found that the variance for the shelf lengths was 9.23 mm² (the shelves were supposed to be 670 mm long in order to fit into the case properly).  Another 27 shelves produced by Basset furniture were examined, and it was found that the variance for those shelf lengths was 0.25 mm².   At the 5% significance level, test the claim that the shelves sold at Wal-Mart are manufactured with more variation than the shelves produced by Basset.   

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