Chapter 7: Problem 12
How does the value of \(\sigma_{\bar{x}}\) change as the sample size increases? Explain.
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Chapter 7: Problem 12
How does the value of \(\sigma_{\bar{x}}\) change as the sample size increases? Explain.
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For a population, \(\mu=125\) and \(\sigma=36\). a. For a sample selected from this population, \(\mu_{\bar{i}}=125\) and \(\sigma_{\bar{i}}=3.6\). Find the sample size. Assume \(n / N \leq .05 .\) b. For a sample selected from this population, \(\mu_{i}-125\) and \(\sigma_{\bar{i}}-2.25\). Find the sample size. Assume \(n / N \simeq 05\).
In an observational study at Turner Field in Atlanta, Georgia, \(43 \%\) of the men were observed not washing their hands after going to the bathroom (Source: Harris Interactive). Assume that this percentage is true for the current population of U.S. men. Let \(\hat{p}\) be the proportion in a random sample of \(110 \mathrm{U} . \mathrm{S}\). men who do not wash their hands after going to the bathroom. Find the mean and standard deviation of the sampling distribution of \(\hat{p}\), and describe its shape.
According to an article on www.PCMag.com, Facebook users spend an average of 190 minutes per month checking and updating their Facebook pages (Source: http://www.pemag.com/article2/ \(0,2817,2342757,00\).asp). Suppose that the current distribution of times spent per month checking and updating their Facebook pages by all users is normally distributed with a mean of 190 minutes and a standard deviation of \(53.4\) minutes. Find the probability that the mean time spent per month checking and updating their Facebook pages by a random sample of 12 Facebook users will be a. within 10 minutes of the population mean b. more than 240 minutes c. at least 20 minutes different than the population mean d. less than 207 minutes
Is the sample proportion a consistent estimator of the population proportion? Explain why or why not.
A company manufactured six television sets on a given day, and these TV sets were inspected for being good or defective. The results of the inspection follow. Good Good \(\quad \begin{array}{llll}\text { Defective } & \text { Defective } & \text { Good } & \text { Good }\end{array}\) r. What proportion of these TV sets are good? b. How many total samples (without replacement) of size five can be selected from this population? c. List all the possible samples of size five that can be selected from this population and calculatc the sample proportion, \(\hat{p}\), of television sets that are good for each sample. Prepare the sampling distribution of \(\hat{p}\). d. For each sample listed in part c. calculate the sampling error.
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