Chap7Stats

Chap7Stats - Review Assessment: Test Chapter 7 User...

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Review Assessment: Test Chapter 7 User Elizabeth S Knowles Submitted 4/2/08 10:43 PM Name Test Chapter 7 Status Completed Score 56 out of 80 points Time Elapsed 1 hours, 20 minutes, and 16 seconds out of 3 hours and 0 minutes allowed. Instructions Question 1 2 out of 2 points Find the appropriate minimum sample size. You want to be 95% confident that the sample variance is within 40% of the population variance. Selected Answer: 56 Correct Answer: 56 Question 2 2 out of 2 points Solve the problem. Find the critical value corresponding to a sample size of 9 and a confidence level of 90 percent. Selected Answer: 2.733 Correct Answer: 2.733 Question 3 2 out of 2 points Use the given degree of confidence and sample data to construct a confidence interval for the population mean μ. Assume that the population has a normal distribution. n = 10, = 12.8, s = 4.9, 95 percent Selected Answer: 9.29 < μ < 16.31 Correct Answer: 9.29 < μ < 16.31 Question 4 2 out of 2 points Solve the problem. The following confidence interval is obtained for a population proportion, p:

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Use these confidence interval limits to find the margin of error, E. Selected Answer: 0.021 Correct Answer: 0.021 Question 5 2 out of 2 points Use the given degree of confidence and sample data to find a confidence interval for the population standard deviation σ. Assume that the population has a normal distribution. The mean replacement time for a random sample of 20 washing machines is 10.2 years and the standard deviation is 2.6 years. Construct a 99% confidence interval for the standard deviation, σ, of the replacement times of all washing machines of this type. Selected Answer: 1.8 yr < σ < 4.3 yr Correct Answer: 1.8 yr < σ < 4.3 yr Question 6 2 out of 2 points Use the given degree of confidence and sample data to construct a confidence interval for the population mean μ. Assume that the population has a normal distribution. A laboratory tested twelve chicken eggs and found that the mean amount of cholesterol was 193 milligrams with s = 15.4 milligrams. Construct a 95 percent confidence interval for the true mean cholesterol content of all such eggs. Selected Answer: 183.2 < μ < 202.8 Correct Answer: 183.2 < μ < 202.8 Question 7 2 out of 2 points Use the given degree of confidence and sample data to construct a confidence interval for the population proportion p. When 306 college students are randomly selected and surveyed, it is found that 115 own a car. Find a 99% confidence interval for the true proportion of all college students who own a car. Selected Answer: 0.305 < p < 0.447 Correct Answer: 0.305 < p < 0.447 Question 8 0 out of 2 points Find the minimum sample size you should use to assure that your estimate of will be within the required margin of error around the population p. Margin of error: 0.01; confidence level: 95%; from a prior study,
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This note was uploaded on 05/27/2008 for the course MTH 157 taught by Professor Spence during the Spring '08 term at VCCS.

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Chap7Stats - Review Assessment: Test Chapter 7 User...

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