Exam 8: Sampling Methods and the Central Umit Theorem

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample Of 25 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. For a 99% confidence interval, what is the critical value needed?

A statistics professor wishes to estimate the average mark on a term test for a course that has Multiple sections and many students. A survey of some of the students registered for the course Reveals the following results: If 95% and 98% confidence intervals were developed to estimate the true term test mean, what Differences would exist?

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample Of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. Develop a 95% confidence interval for the mean annual Consumption of sugar.

Dr. Patton is a professor of English. Recently she counted the number of misspelled works in a Group of student essays. She noted the distribution of misspelled words per essay followed the Normal distribution with a standard deviation of 2.44 words per essay. For her Tuesday class of 50 Students, the mean number of misspelled words per essay was 6.05. Construct a 99% confidence Interval for the mean number of misspelled words in the population of student essays.

A survey of 25 grocery stores revealed that the average price of a 4-litre bag of milk was $2.98 with A standard error of $0.10. What is the 95% confidence interval to estimate the true cost of a 4-litre Bag of milk?

A statistics professor wishes to estimate the average mark on a term test for a course that has Multiple sections and many students. A survey of some of the students registered for the course Reveals the following results: The student from the course wonders whether the population mean could have been 60 or 80.

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample Of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. For a 99% confidence interval, what is the critical value needed?

A manager of a local store wants to estimate the mean amount spent per shopping visit by Customers. Summary statistics from a sample taken reveal the following: If 90% and 95% confidence intervals were developed to estimate the true shopping expenditure, What similarities would exist?

College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 80 messages that were not business related. The 95% Confidence interval for the population proportion is:

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample Of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. Develop a 99% confidence interval for the mean annual Consumption of sugar.

The z-value associated with a 96% level of confidence is:

i. One factor in determining the size of a sample is the degree of confidence selected. This is Usually 0.95 or 0.99, but it may be any degree of confidence you specify. ii. One factor in determining the size of a sample is the maximum allowable error that you must Decide on. It is the maximum error you will tolerate at a specified level of confidence. iii. The variation in the population as measured by the standard deviation has little or no effect in Determining the size of a sample selected from the population.

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample Of 16 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. For a 95% confidence interval, what is the critical value needed?

A survey of 25 grocery stores revealed that the average price of a 4-litre bag of milk was $2.98 with A standard error of $0.10. If 90% and 95% confidence intervals were developed to estimate the true Cost of a 4-litre bag of milk, what similarities would they have?

College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 80 messages that were not business related. The 90% Confidence interval for the population proportion is:

i. The Student t distribution has a greater spread than does the z distribution. As a result, the critical Values of t for a given level of significance are larger in magnitude than the corresponding z critical Values. ii. The test statistic t has n-1 degrees of freedom. iii. William S. Gosset, a brewmaster, developed the t test for the Guinness Brewery in Ireland, who Published it in 1908 using the pen name "Student."

The Sugar Producers Association wants to estimate the mean yearly sugar consumption. A sample Of 25 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. For a 95% confidence interval, what is the critical value needed?

A survey of an urban university (population of 25,450) showed that 870 of 1,100 students sampled Supported a fee increase to fund improvements to the student recreation center. Using the 95% Level of confidence, what is the confidence interval?

College X is concerned about their employees making use of their email for non-business purposes. You have been approached to assist in this matter. College X decides on a 95% confidence level And state that the estimation proportion must be within 2 percent of the population proportion. A Pilot survey reveals that 10 out of 50 emails sampled were not for business purposes. How many Emails should be surveyed to meet your requirements?

The distribution of Student's t has