Chapter 7: Problem 29
If all possible samples of the same (large) size are selected from a population, what percentage of all the sample means will be within \(1.5\) standard deviations \(\left(\sigma_{\bar{x}}\right)\) of the population mean?
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Chapter 7: Problem 29
If all possible samples of the same (large) size are selected from a population, what percentage of all the sample means will be within \(1.5\) standard deviations \(\left(\sigma_{\bar{x}}\right)\) of the population mean?
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The GPAs of all students enrolled at a large university have an approximately normal distribution with a mean of \(3.02\) and a standard deviation of \(.29\). Find the probability that the mean GPA of a random sample of 20 students selected from this university is a. \(3.10\) or higher b. \(2.90\) or lower c. \(2.95\) to \(3.11\)
According to the central limit theorem, the sampling distribution of \(\hat{p}\) is approximately normal when the sample is large. What is considered a large sample in the case of the proportion? Briefly explain.
Briefly explain the meaning of a population probability distribution and a sampling distribution. Give an example of each.
What is the estimator of the population proportion? Is this estimator an unbiased estimator of \(p ?\) Explain why or why not.
According to a Gallup poll conducted April \(3-6,2014,21 \%\) of Americans aged 18 to 29 said that college loans and/or expenses were the top financial problem facing their families. Assume that this percentage is true for the current population of Americans aged 18 to \(29 .\) Let \(\hat{p}\) be the proportion in a random sample of 900 Americans aged 18 to 29 who hold the above opinion. Find the mean and standard deviation of the sampling distribution of \(\hat{p}\) and describe its shape.
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