Exam 8: Sampling Methods and the Central Umit Theorem

How large a sample of government employees should be taken if we want to estimate with 98% Confidence the mean salary to within $2,000? The population standard deviation is assumed to be $10,500. (Round up to the nearest whole number)

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 90% 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 following summarizes the average price of Air Canada stock at the end of 20 randomly Selected weeks in 2000. Determine a 98% confidence interval for the average TSE 300 stock index in 2000.

College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 60 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 25 people reveals the mean yearly consumption to be 27 kg with a sample standard deviation of 9 kg. Assume a normal population. Develop a 90% confidence interval for the mean annual Consumption of sugar.

The proportion of junior executives leaving large manufacturing companies within three years is to Be estimated within 3 percent. The 0.95 degree of confidence is to be used. A study conducted Several years ago revealed that the percent of junior executives leaving within three years was 21. To update this study, the files of how many junior executives should be studied?

(i. The point estimate states the range within which a population parameter probably lies. (ii.. The measure of confidence that one has in the interval estimate is called degree of level of Confidence. (iii) For a sampling distribution of the means, 95% percent of the means would be between ± 1.96 Standard deviations.

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 8 out of 50 emails sampled were not for business purposes. How many Emails should be surveyed to meet your requirements?

The Dean of the Business School wants to estimate the mean number of hours worked per week by Students. A sample of only 12 students showed a mean of 24 hours with a standard deviation of 4 Hours. Find the 95 percent confidence interval for the population mean.

Determine the sample size that is required to estimate a population mean to within 0.4 units with a 99% confidence when the population standard deviation is 1.75.

When a confidence interval for a population mean is constructed from sample data,

A random sample of 85 group leaders, supervisors, and similar personnel revealed that on the Average a person spent 6.5 years on the job before being promoted. The standard deviation of the Sample was 1.7 years. What is the 95% confidence interval for the true population mean?

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 90% and 95% confidence intervals were developed to estimate the true term test mean, what Similarities would exist?

(i. The interval estimate states the range within which a population parameter probably lies. (ii.. The measure of confidence that one has in the interval estimate is called degree of level of Confidence. (iii) For a sampling distribution of the means, 95% percent of the means would be between ± 1.96 Standard deviations.

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 90% confidence interval for the mean annual Consumption of sugar.

College X is concerned about their employees making use of their email for non-business purposes. A random sample of 400 e-mails discovered 60 messages that were not business related. The 99% Confidence interval for the population proportion is:

(i. The interval estimate states the range within which a population parameter probably lies. (ii.. The measure of confidence that one has in the interval estimate is called degree of level of Confidence. (iii) For a sampling distribution of the means, 90% percent of the means would be between ± 1.96 Standard deviations.

Recently, a university surveyed recent graduates of the English Department for their starting Salaries. Four hundred graduates returned the survey. The average salary was $25,000. The Population standard deviation is known to be $2,500. Interpret the results of the 95% confidence interval.

The following summarizes the amount of snowfall in Ontario over the past number of years. You wonder whether the population mean could have been 2000 or 1900.

Recently, a university surveyed recent graduates of the English Department for their starting Salaries. Four hundred graduates returned the survey. The average salary was $55,000. The Population standard deviation is known to be $2,500. What is the 95% confidence interval for the mean salary of all graduates from the English Department?