10th Edition

ISBN: 9780321989178

Author: Neil A. Weiss

Publisher: PEARSON

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Textbook Question

Chapter 8.3, Problem 130E

Preliminary data analyses indicate that you can reasonably apply the t-interval procedure (Procedure 8.2 on page 355) in Exercises 8.129–8.134.

8.130 Digital Viewing Times. According to eMarketer, the average time spent per day with digital media in 2010 was 3 hours and 14 minutes. For last year, a random sample of 20 American adults spent the following number of hours per day with digital media.

Chapter 8.3, Problem 130E, Preliminary data analyses indicate that you can reasonably apply the t-interval procedure (Procedure

Find and interpret, a 90% confidence interval for last year’s mean time spent per day with digital media by American adults. (Note: x ¯ = 5.16 hr and s = 2.30 hr.)

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...

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Chapter 8.3, Problem 129E

Chapter 8.3, Problem 131E

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In each of Exercises, use the technology of your choice to decide whether applying the t-interval procedure to obtain a confidence interval for the population mean in question appears reasonable. Explain your answers. Shoe and Apparel E-Tailers. In the special report “Mousetrap: The Most-Visited Shoe and Apparel E-tailers” (Footwear News, Vol. 58), we found the following data on the average time, in minutes, spent per user per month from January to June of one year for a sample of 15 shoe and apparel retail websites. 13.3 9.0 11.1 9.1 8.4 15.6 8.1 8.3 13.0 17.1 16.3 13.5 8.0 15.1 5.8

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Chapter 8 Solutions

Introductory Statistics (10th Edition)

Ch. 8.1 - The value of a statistic used to estimate a...Ch. 8.1 - What is a confidence-interval estimate of a...Ch. 8.1 - Prob. 3E Ch. 8.1 - Prob. 4E Ch. 8.1 - Prob. 5E Ch. 8.1 - Suppose that you lake 500 simple random samples...Ch. 8.1 - Prob. 7E Ch. 8.1 - A simple random sample is taken from a population...Ch. 8.1 - Refer to Exercise 8.7 and find a point estimate...Ch. 8.1 - Prob. 10E

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Solution Summary: The author analyzes the 90% confidence interval of the population mean time spent per day by American adults with digital media.

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