Question 1

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:

Accepted Answer

The population of interest is the entire group of 3.5 million registered voters in the state, as the councilman is running for senator of the state and needs to know the voting intentions of the entire population, not just those who were surveyed. The 8,000 registered voters interviewed and the 46% who plan to vote for him are both samples within the larger population. All the residents of the state is too broad of a population as not all residents are registered voters.

Question 2

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

Accepted Answer

A descriptive measure that is computed from a population is called a parameter. Sample and statistic are computed from a sample, whereas population represents the entire group being studied.

Question 3

A descriptive measure that is computed from a sample is called a:

Accepted Answer

Descriptive measures computed from a sample are called statistics. A parameter is a descriptive measure that is computed from a population, while population and sample refer to the entire and selected group of individuals, respectively.

Question 4

A descriptive measure of a sample is called a parameter.

Accepted Answer

A descriptive measure of a sample is called a statistic. Parameters are descriptive measures of a population, not a sample.

Question 5

A company has developed a new computer microprocessor whose average lifetime is unknown.In order to estimate this average,300 microprocessors are randomly selected from a large production line and tested; their average lifetime is found to be 7 years.The 300 microprocessors represent a:

Accepted Answer

The 300 microprocessors represent a sample, as it is a subset of the larger population of all the microprocessors produced by the company.

Question 6

The significance level measures the proportion of the time an inference about a population will be correct in the long run.

Accepted Answer

The significance level, also known as alpha, is the threshold chosen by the researcher to test the null hypothesis. It represents the probability of rejecting the null hypothesis when it is true, and is typically set at 0.05 (5%). It does not measure the proportion of times an inference about a population will be correct in the long run. This concept is related to the concept of confidence level, which measures the proportion of times the true population parameter will fall within the confidence interval calculated from a sample in the long run.

Question 7

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

Accepted Answer

Statistical inference involves using sample data to make conclusions or predictions about a larger population. It is based on the principles of probability and statistics and involves making inferences about the population based on the characteristics of the sample.

Question 8

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

Accepted Answer

A significance level (often denoted as alpha or α) is a measure used in hypothesis testing to determine the threshold at which the null hypothesis is rejected, thus it directly relates to the reliability of a statistical inference. It essentially indicates how strong the evidence must be before we can conclude that an effect is statistically significant and not just due to random chance.

Question 9

The confidence level is the proportion of times that an estimating procedure will be wrong in the long run.

Accepted Answer

The confidence level is the proportion of times that an estimating procedure will be correct in the long run.

Question 10

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:

Accepted Answer

The average lifetime of the 100 engines is a statistic because it is based on a sample (the 100 engines selected from the production line) and is used to estimate the population parameter (the true average lifetime of all engines produced by the company).

Question 11

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?

Accepted Answer

Inferential statistics is applied when using a sample to make predictions or inferences about a population. In this case, the average GPA of the 100 students is used as an estimate for the average GPA of all students at LearnAll University.

Question 12

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

Accepted Answer

A statistic is a descriptive measure that is calculated from a sample, whereas a parameter is a descriptive measure calculated from a population.

Question 13

A population is the group of all items of interest to a statistics practitioner.

Accepted Answer

A population is defined as the entire group of items that share at least one common characteristic and are of interest to a statistics practitioner.

Question 14

A statistic is typically a known quantity while a parameter is typically an unknown quantity.

Accepted Answer

This statement is true. A statistic is a numerical summary of a sample, and is known because it can be calculated from the data. A parameter is a numerical summary of a population, and is generally unknown because it cannot be directly observed and must be estimated from sample data.

Question 15

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.

Accepted Answer

The proportion of the 350 employees who favor the health insurance plan represents a statistic, not a parameter, because it is a measure derived from a sample of the population, not the entire population itself.

Question 16

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.

Accepted Answer

A statistic is a numerical value calculated from a sample of data, and in this case, the percentage of marketing majors in the sample of 350 students is a statistic.

Question 17

A descriptive measure of a population is called a parameter.

Accepted Answer

This statement is correct. Parameters are descriptive measures of a population, and they are typically represented by Greek letters (e.g., μ for the population mean). In contrast, statistics are descriptive measures of a sample (i.e., a subset of the population), and they are typically represented by Roman letters (e.g., x̄ for the sample mean).

Question 18

A company has developed a new power cell and wants to estimate its average lifetime.A random sample of 650 power cells is tested and the average lifetime of this sample is found to be 315 hours.The 315 hours is the value of a:

Accepted Answer

The 315 hours represents the average lifetime of the sample of 650 power cells that were tested. Therefore, it is a statistic, which is a numerical summary of a sample. A parameter, on the other hand, is a numerical summary of an entire population.

Question 19

35% of a sample of 300 professional baseball players indicated that their parents did not play baseball.Based on this sample,we estimate that approximately 35% of the parents of all professional baseball players did not play baseball,plus or minus 5%.This is an example of using inferential statistics.

Accepted Answer

This statement is true as the sample of 300 professional baseball players is used to estimate the proportion of all professional baseball players' parents who did not play baseball. This estimation involves inferential statistics, which uses a sample to make predictions or inferences about the larger population.

Question 20

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.

Accepted Answer

A confidence level of 80% means that if you were to take many random samples and construct confidence intervals for each, approximately 80% of those intervals would contain the true population mean.

Quiz 1: What Is Statistics