10th Edition

ISBN: 9780321989178

Author: Neil A. Weiss

Publisher: PEARSON

Concept explainers

In a 2-proportion test, two separate proportions are measured at the same time, and their similarity is evaluated. It is also known as a 2-proportion z-test, and a comparison of two different proportions is done in this method.

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Textbook Question

Chapter 12, Problem 15RP

Bulletproof Vests. In the New York Times article “A Common Police Vest Fails the Bulletproof Test,” E. Lichtblau reported on a U.S. Department of Justice study of 103 bulletproof vests containing fiber known as Zylon. In ballistics tests, only 4 of these vests produced acceptable safety outcomes (and resulted in immediate changes in federal safety guidelines). Find a 95% confidence interval for the proportion of all such vests that would produce acceptable safety outcomes by using the

a. one-proportion z-interval procedure.
b. one-proportion plus-four z-interval procedure. (See page 556 for the details of this procedure.)
c. Explain the large discrepancy between the two methods.
d. Which confidence interval would you use? Explain your answer.

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Chapter 12, Problem 14RP

Chapter 12, Problem 1FDA

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Bulletproof Vests. In the article “A Common Police Vest Fails the Bulletproof Test,” E. Lichtblau reported on a U.S. Department of Justice study of 103 bulletproof vests containing a fiber known as Zylon. In ballistics tests, only 4 of these vests produced acceptable safety outcomes (and resulted in immediate changes in federal safety guidelines). Find a 95% confidence interval for the proportion of all such vests that would produce acceptable safety outcomes by using the a. one-proportion z-interval procedure. b. one-proportion plus-four z-interval procedure. (See page 556 for the details of this procedure.) c. Explain the large discrepancy between the two methods. d. Which confidence interval would you use? Explain your answer.

Chapter 12 Solutions

Introductory Statistics (10th Edition)

Ch. 12.1 - Why is statistical inference generally used to...Ch. 12.1 - Prob. 3E Ch. 12.1 - Prob. 4E Ch. 12.1 - Regarding a sample proportion: a. What is it? b....Ch. 12.1 - Regarding the phrase number of successes: a. For...Ch. 12.1 - For what is the phrase number of failures an...Ch. 12.1 - Explain the relationships among the sample...Ch. 12.1 - Prob. 9E Ch. 12.1 - Repeat parts (b)(e) of Exercise 12.9 for samples...Ch. 12.1 - Prob. 11E

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Solution Summary: The author explains the one-proportion z-interval procedure to obtain the confidence interval for a population proportion, p.

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