Chapter 8: Problem 8
Explain what the term sampling variability means in the context of using a sample proportion to estimate a population proportion.
Chapter 8: Problem 8
Explain what the term sampling variability means in the context of using a sample proportion to estimate a population proportion.
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Get started for freeConsider the following statement: The proportion of all students enrolled at a particular university during 2012 who lived on campus was \(\mathbf{0 . 2 1}\). a. Is the number that appears in boldface in this statement a sample proportion or a population proportion? b. Which of the following use of notation is correct, \(p=0.21\) or \(\hat{p}=0.21 ?\)
Consider the following statement: In a sample of 20 passengers selected from those who flew from Dallas to New York City in April 2012, the proportion who checked luggage was \(\underline{0.45}\). a. Is the number that appears in boldface in this statement a sample proportion or a population proportion? b. Which of the following use of notation is correct, \(p=0.45\) or \(\hat{p}=0.45 ?\)
Explain why there is sample-to-sample variability in \(\hat{p}\) but not in \(p\).
The article "Thrillers" (Newsweek, April 22,1985 ) stated, "Surveys tell us that more than half of America's college graduates are avid readers of mystery novels." Let \(p\) denote the actual proportion of college graduates who are avid readers of mystery novels. Consider a sample proportion \(\hat{p}\) that is based on a random sample of 225 college graduates. If \(p=0.5,\) what are the mean value and standard deviation of the sampling distribution of \(\hat{p}\) ? Answer this question for \(p=0.6 .\) Is the sampling distribution of \(\hat{p}\) approximately normal in both cases? Explain.
A random sample of 50 registered voters in a particular city included 32 who favored using city funds for the construction of a new recreational facility. For this sample, \(\hat{p}=\frac{32}{50}=\) 0.64 . If a second random sample of 50 registered voters was selected, would it surprise you if \(\hat{p}\) for that sample was not equal to 0.64 ? Why or why not?
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