Exam 8: Sampling Methods and the Central Umit Theorem

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 Population was 1.7 years. Find the 95% confidence interval for the population mean.

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 95% confidence interval for the mean annual Consumption of sugar.

In order to construct a 90% confidence interval for the population mean when the population Standard deviation is unknown and the sample size is 18, you should use the t-value indicated as:

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. If university Officials say that at least 70% of the voting student population support the fee increase, what Conclusion can be drawn based on a 95% level of confidence?

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 sample of 25 is selected from a known population of 100 elements. What is the finite population Correction factor?

There are 2,000 eligible voters in a precinct. Despite protests from knowledgeable persons that a Sample size of 500 was too large in relation to the total, the 500 selected at random were asked to Indicate whether they planned to vote for the Liberal incumbent or the Conservative challenger. Of The 500 surveyed, 350 said they were going to vote for the Liberal incumbent. Using the 0.99 Confidence coefficient, what are the confidence limits for the proportion that plan to vote for the Liberal incumbent?

In order to construct a 95% confidence interval for the population mean when the population Standard deviation is unknown and the sample size is 15, you should use the t-value indicated as:

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 99% Level of confidence, what is the confidence interval?

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

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 95% confidence interval to estimate the true cost of the DVD?

The following summarizes the average price of Air Canada stock at the end of 20 randomly Selected weeks in 2000. Determine a 95% confidence interval for the average Air Canada stock price in 2000.

i. The t distribution is based on the assumption that the population of interest is normal or nearly Normal. ii. The t distribution is a discrete distribution. iii. There is not one t distribution, but rather a "family" of t distributions.

A sample of 100 students is selected from a known population of 1,000 students to construct a 95% Confidence interval for the average SAT score. What correction factor should be used to compute The standard error?

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

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 40 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. For a 90% confidence interval, what is the critical value needed?

Which of the following is NOT necessary to determine how large a sample to select from a Population?

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 90% confidence interval, what is the critical value needed?