Exam 1: What Is Statistics

You take a random sample to estimate a population mean and your results have a confidence level of 80%. That means the process you used will give you correct results 80% of the time.

A company has developed a new engine whose average lifetime is unknown. In order to estimate this average, 100 engines are randomly selected from a large production line and tested; their average lifetime is found to be 11 years. The 11 years represents a:

A summary measure that is computed from a population is called a:

Briefly describe the difference between a population and a sample and give an example of each.

A councilman who is running for the office of senator of a state with 3.5 million registered voters commissions a survey. In the survey, 46% of the 8,000 registered voters interviewed say they plan to vote for him. The population of interest is:

The Human Resources Director at Florida Atlantic University wishes to develop an employee benefits package. To get an idea of what components of a benefits package are most important, he selects 350 employees at random and asks them for their opinions. Numerically summarizing the preferences of these 350 employees is an example of doing ____________________ statistics.

A study is under way to determine the average height of all 63,000 adult walnut trees in a certain national forest. The heights of 950 randomly selected adult walnut trees are measured and analyzed. The sample in this study is:

A resort employs 3,500 managers and staff. To ascertain their employees' opinions of a proposed health insurance plan, 350 employees are surveyed at random. The proportion of the 350 employees who favor the health insurance plan represents a parameter in this scenario.

A random sample of 100 students is taken at LearnAll University and it's found that their average GPA is 3.1. If this information is used to help estimate the average GPA for all students at LearnAll University, which branch of statistics was applied?

A manufacturer of microwave ovens wants to know what percentage of all of their microwave ovens are defective. When 450 of their microwave ovens are selected at random and examined, 0.4% are found to be defective. a.Describe the population of interest. b.Describe the sample. c.Describe/find the parameter. d.Describe/find the statistic. e.Is the 0.4% a parameter or a statistic in this scenario? Why?

In a sample of 350 students selected from a large college of business, 25% are found to be marketing majors. The 25% is a statistic.

Identify each of the following as a use of descriptive statistics or inferential statistics. a.Finding the weights of a sample of 85 manufacturer parts. b.Calculating the average weight of 125 boxes shipped by FedEx. c.Estimating the percentage of the U.S. population that will vote for your favorite candidate in the next presidential election. d.Selecting a random sample of 190 babies born last year and using this information to estimate the birth weight of all babies born last year. e.Randomly selecting 225 cans of a brand of peas and using their average weight to decide whether the 15 oz. label on the cans is truthful or not.

Statistical inference is the process of making an estimate, prediction, or decision about a population based on sample data.

Which of the following is a measure of the reliability of a statistical inference?

The Human Resources Director of a large hospital wants to determine the percentage of all employees who favor a newly proposed benefits package. He selects 300 employees at random and finds that 85% approve the newly proposed package. The percentage of all employees of this company who favor the newly proposed package is a(n) ____________________.

A study is under way to determine the average height of all 29,000 adult pine trees in a certain national forest. The heights of 600 randomly selected adult pine trees are measured and analyzed. The parameter in the study is:

Which of the following represents a population, as opposed to a sample?

What name do we give to a descriptive measure of a sample?

A summary measure that is computed from a sample is called a statistic.

A descriptive measure of a population is called a parameter.