Exam 8: Estimation and Confidence Intervals

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: Determine a 95% confidence interval for the mean amount spent.

Suppose 1,600 of 2,000 registered voters sampled said they planned to vote for a particular candidate. Using the 0.95 degree of confidence, what is the interval estimate for the population proportion (to the nearest tenth of a percent)?

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 98% confidence interval to estimate the true cost of a 4-litre bag of milk?

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 99% 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?

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 95% and 98% confidence intervals were developed to estimate the true shopping expenditure, what differences 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 60 messages that were not business related. The 95% Confidence interval for the population proportion is:

A survey of 144 retail stores revealed that the average price of a DVD was $375 with a standard error of $20. What is the 99% confidence interval to estimate the true cost of the DVD?

The ______estimate states the range within which a population parameter probably lies.

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 99% Confidence interval for the population proportion is:

A student wanted to quickly construct a 95% confidence interval for the average age of students in her statistics class. She randomly selected 9 students. Their average age was 19.1 years with a standard deviation of 1.5 years. What is the 95% confidence interval for the population mean?

What kind of distribution is the t distribution?

The distribution of Student's t is

The following summarizes the amount of snowfall in Ontario over the past number of years. Determine a 98% confidence interval for the average annual snowfall.

A student wanted to quickly construct a 95% confidence interval for the average age of students in her statistics class. She randomly selected 9 students. Their average age was 19.1 years with a standard deviation of 1.5 years. What is the best point estimate for the population mean?

A pharmaceutical company wanted to estimate the population mean of monthly sales for their 250 sales people. Forty sales people were randomly selected. Their mean monthly sales were $10,000 with a standard deviation of $1,000. Construct a 95% confidence interval for the population mean.

The following summarizes the amount of snowfall in Ontario over the past number of years. Determine a 95% confidence interval for the average annual snowfall.

Which of the following would be used as a point estimate for the population mean (µ)?

The following summarizes the amount of snowfall in Ontario over the past number of years. If 95% and 98% confidence intervals were developed to estimate the true average annual snowfall, what differences would exist?

A student wanted to quickly construct a 95% confidence interval for the average age of students in her statistics class. She randomly selected 9 students. Their average age was 19.1 years with a standard deviation of 1.5 years. What is the 99% confidence interval for the population mean?

How does the t distribution differ from the standard z distribution?