Question 1

To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except​

Accepted Answer

A)  ​use the estimated σ from a previous study. 
B)  ​use the sample standard deviation from a preliminary sample. 
C)  ​use judgment or a best guess. 
D)  use .5 as an estimate. 
A)  ​use the estimated σ from a previous study. 
B)  ​use the sample standard deviation from a preliminary sample. 
C)  ​use judgment or a best guess. 
D)  use .5 as an estimate.

Question 2

From a population that is not normally distributed and whose standard deviation is not known, a sample of 50 items is selected to develop an interval estimate for µ.Which of the following statements is true?​

Accepted Answer

A)  ​The standard normal distribution can be used. 
B)  ​The t distribution with 50 degrees of freedom must be used. 
C)  ​The t distribution with 49 degrees of freedom must be used. 
D)  ​The sample size must be increased in order to develop an interval estimate. 
A)  ​The standard normal distribution can be used. 
B)  ​The t distribution with 50 degrees of freedom must be used. 
C)  ​The t distribution with 49 degrees of freedom must be used. 
D)  ​The sample size must be increased in order to develop an interval estimate.

Question 3

A new brand of chocolate bar is being market tested.Four hundred of the new chocolate bars were given to consumers to try.The consumers were asked whether they liked or disliked the chocolate bar.You are given their responses below.   ​ 
a.
What is the point estimate for the proportion of people who liked the chocolate bar?
b.
Construct a 95% confidence interval for the true proportion of people who liked the chocolate bar.
c.
With a .95 probability, how large of a sample needs to be taken to provide a margin of error of 1.5% or less?
​

Accepted Answer

​
a.
.80
b

Question 4

A random sample of 100,000 credit sales in a department store showed an average sale of $87.25.From past data, it is known that the standard deviation of the population is $20.00.Determine the standard error of the mean.

Accepted Answer

A)  .0632 
B)  .0002 
C)  20.00 
D)  .0141 
A)  .0632 
B)  .0002 
C)  20.00 
D)  .0141

Question 5

A simple random sample of 36 items resulted in a sample mean of 40 and a standard deviation of 12.Construct a 95% confidence interval for the population mean.

Accepted Answer

The answer of A simple random sample of 36 items...

Question 6

The average score of a sample of 87 senior business majors at UTC who took the Graduate Management Admission Test was 510 with a standard deviation of 36.Provide a 98% confidence interval for the mean of the population.

Accepted Answer

500.85 to

Question 7

If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the

Accepted Answer

A)  width of the confidence interval to increase. 
B)  width of the confidence interval to decrease. 
C)  width of the confidence interval to remain the same. 
D)  sample size to increase. 
A)  width of the confidence interval to increase. 
B)  width of the confidence interval to decrease. 
C)  width of the confidence interval to remain the same. 
D)  sample size to increase.

Question 8

It is known that the population variance (σ2) is 125.At 95% confidence, what sample size should be taken so that the margin of error does not exceed 3?

Accepted Answer

A)  52 
B)  53 
C)  54 
D)  55 
A)  52 
B)  53 
C)  54 
D)  55

Question 9

A random sample of 49 statistics examinations was taken.The average score, in the sample, was 84 with a variance of 12.25.The 95% confidence interval for the average examination score of the population of the examinations is

Accepted Answer

A)  83.45 to 84.55. 
B)  80.07 to 87.93. 
C)  83.29 to 84.71. 
D)  80.5 to 87.5. 
A)  83.45 to 84.55. 
B)  80.07 to 87.93. 
C)  83.29 to 84.71. 
D)  80.5 to 87.5.

Question 10

We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor.What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?

Accepted Answer

A)  625 
B)  626 
C)  600 
D)  601 
A)  625 
B)  626 
C)  600 
D)  601

Question 11

In a campaign to eliminate non-returnable beverage containers, a poll of 600 voters showed 210 of them opposed the container control bill.Develop a 92% confidence interval estimate for the proportion of all the voters who opposed this bill.

Accepted Answer

.316 to .3

Question 12

A university planner is interested in determining the percentage of spring semester students who will attend summer school.She takes a pilot sample of 160 spring semester students discovering that 56 will return to summer school.
a.
Construct a 95% confidence interval estimate for the percentage of spring semester students who will return to summer school.
b.
Using the results of the pilot study with a .95 probability, how large of a sample would have to be taken to provide a margin of error of 3% or less?

Accepted Answer

​
a.
.276

Question 13

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 64 business students over a one-week period.Assume the population standard deviation is 1.6 hours.With a .95 probability, the margin of error is approximately

Accepted Answer

A)  .392. 
B)  1.96. 
C)  .20. 
D)  1.645. 
A)  .392. 
B)  1.96. 
C)  .20. 
D)  1.645.

Question 14

In 2015, approximately 136,943,000 people visited an emergency room in the United States.Of these, approximately 12,263,000 were subsequently admitted to the hospital.Provide a 99% confidence interval for the proportion of people visiting an emergency room who were subsequently admitted to the hospital.

Accepted Answer

A)  .089485 to .089611 
B)  .089491 to .089605 
C)  .089500 to .089596 
D)  .089548 to .089548 
A)  .089485 to .089611 
B)  .089491 to .089605 
C)  .089500 to .089596 
D)  .089548 to .089548

Question 15

A random sample of 25,000 ACT test takers had an average score of 21 with a standard deviation of 5.With a .95 probability, determine the margin of error.

Accepted Answer

A)  .0277 
B)  .0568 
C)  .2603 
D)  .0620 
A)  .0277 
B)  .0568 
C)  .2603 
D)  .0620

Question 16

A sample of 144 cans of coffee showed an average weight of 32 ounces.The standard deviation of the population is known to be 1.4 ounces.
a.
Construct a 68.26% confidence interval for the mean of the population.
b.
Construct a 97% confidence interval for the mean of the population.
c.
Discuss why the answers in Parts a and b are different.

Accepted Answer

​
a.
31.88 to 32.12 ounces
b.

Question 17

In a random sample of 400 residents of Chattanooga, 320 residents indicated that they voted for the Democratic candidate in the last presidential election.Develop a 95% confidence interval estimate for the proportion of all Chattanooga residents who voted for the Democratic candidate.

Accepted Answer

The answer of In a random sample of 400 residents...

Question 18

A random sample of 81 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 300.The t value needed to develop the 95% confidence interval for the population mean SAT score is

Accepted Answer

A)  1.96. 
B)  1.998. 
C)  1.645. 
D)  1.28. 
A)  1.96. 
B)  1.998. 
C)  1.645. 
D)  1.28.

Question 19

A sample of 200 elements from a population with a known standard deviation is selected.For an interval estimation of μ, the proper distribution to use is the

Accepted Answer

A)  normal distribution. 
B)  t distribution with 200 degrees of freedom. 
C)  t distribution with 201 degrees of freedom. 
D)  t distribution with 199 degrees of freedom. 
A)  normal distribution. 
B)  t distribution with 200 degrees of freedom. 
C)  t distribution with 201 degrees of freedom. 
D)  t distribution with 199 degrees of freedom.

Question 20

​The general form of an interval estimate of a population mean or a population proportion is the _____ plus and minus the _____.

Accepted Answer

A)  ​population mean, standard error 
B)  population proportion, standard error 
C)  ​point estimate, margin of error 
D)  ​planning value, confidence coefficient 
A)  ​population mean, standard error 
B)  population proportion, standard error 
C)  ​point estimate, margin of error 
D)  ​planning value, confidence coefficient

To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except

From a population that is not normally distributed and whose standard deviation is not known, a sample of 50 items is selected to develop an interval estimate for µ.Which of the following statements is true?

A random sample of 100,000 credit sales in a department store showed an average sale of $87.25.From past data, it is known that the standard deviation of the population is $20.00.Determine the standard error of the mean.

A simple random sample of 36 items resulted in a sample mean of 40 and a standard deviation of 12.Construct a 95% confidence interval for the population mean.

The average score of a sample of 87 senior business majors at UTC who took the Graduate Management Admission Test was 510 with a standard deviation of 36.Provide a 98% confidence interval for the mean of the population.

If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the

It is known that the population variance (σ²) is 125.At 95% confidence, what sample size should be taken so that the margin of error does not exceed 3?

A random sample of 49 statistics examinations was taken.The average score, in the sample, was 84 with a variance of 12.25.The 95% confidence interval for the average examination score of the population of the examinations is

We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor.What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?

In a campaign to eliminate non-returnable beverage containers, a poll of 600 voters showed 210 of them opposed the container control bill.Develop a 92% confidence interval estimate for the proportion of all the voters who opposed this bill.

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 64 business students over a one-week period.Assume the population standard deviation is 1.6 hours.With a .95 probability, the margin of error is approximately

A random sample of 25,000 ACT test takers had an average score of 21 with a standard deviation of 5.With a .95 probability, determine the margin of error.

In a random sample of 400 residents of Chattanooga, 320 residents indicated that they voted for the Democratic candidate in the last presidential election.Develop a 95% confidence interval estimate for the proportion of all Chattanooga residents who voted for the Democratic candidate.

A random sample of 81 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 300.The t value needed to develop the 95% confidence interval for the population mean SAT score is

A sample of 200 elements from a population with a known standard deviation is selected.For an interval estimation of μ, the proper distribution to use is the

The general form of an interval estimate of a population mean or a population proportion is the _ plus and minus the _.

Data and Statistics

Descriptive Statistics: Tabular and Graphical Displays

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Tests

Inference About Means and Proportions With Two Populations

Inferences About Population Variances

Comparing Multiple Proportions, Tests of Independence and Goodness of Fit

Experimental Design and Analysis of Variance

Simple Linear Regression

Multiple Regression

Filters

Exam 8: Interval Estimation

To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except​

From a population that is not normally distributed and whose standard deviation is not known, a sample of 50 items is selected to develop an interval estimate for µ.Which of the following statements is true?​

A random sample of 100,000 credit sales in a department store showed an average sale of $87.25.From past data, it is known that the standard deviation of the population is $20.00.Determine the standard error of the mean.

A simple random sample of 36 items resulted in a sample mean of 40 and a standard deviation of 12.Construct a 95% confidence interval for the population mean.

The average score of a sample of 87 senior business majors at UTC who took the Graduate Management Admission Test was 510 with a standard deviation of 36.Provide a 98% confidence interval for the mean of the population.

If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the

It is known that the population variance (σ2) is 125.At 95% confidence, what sample size should be taken so that the margin of error does not exceed 3?

A random sample of 49 statistics examinations was taken.The average score, in the sample, was 84 with a variance of 12.25.The 95% confidence interval for the average examination score of the population of the examinations is

We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor.What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?

In a campaign to eliminate non-returnable beverage containers, a poll of 600 voters showed 210 of them opposed the container control bill.Develop a 92% confidence interval estimate for the proportion of all the voters who opposed this bill.

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 64 business students over a one-week period.Assume the population standard deviation is 1.6 hours.With a .95 probability, the margin of error is approximately

A random sample of 25,000 ACT test takers had an average score of 21 with a standard deviation of 5.With a .95 probability, determine the margin of error.

In a random sample of 400 residents of Chattanooga, 320 residents indicated that they voted for the Democratic candidate in the last presidential election.Develop a 95% confidence interval estimate for the proportion of all Chattanooga residents who voted for the Democratic candidate.

A random sample of 81 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 300.The t value needed to develop the 95% confidence interval for the population mean SAT score is

A sample of 200 elements from a population with a known standard deviation is selected.For an interval estimation of μ, the proper distribution to use is the

​The general form of an interval estimate of a population mean or a population proportion is the _____ plus and minus the _____.

Data and Statistics

Descriptive Statistics: Tabular and Graphical Displays

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling and Sampling Distributions

Hypothesis Tests

Inference About Means and Proportions With Two Populations

Inferences About Population Variances

Comparing Multiple Proportions, Tests of Independence and Goodness of Fit

Experimental Design and Analysis of Variance

Simple Linear Regression

Multiple Regression

Filters

To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except

From a population that is not normally distributed and whose standard deviation is not known, a sample of 50 items is selected to develop an interval estimate for µ.Which of the following statements is true?

It is known that the population variance (σ²) is 125.At 95% confidence, what sample size should be taken so that the margin of error does not exceed 3?

The general form of an interval estimate of a population mean or a population proportion is the _ plus and minus the _.