Chapter 9 2 None The Above 926 Find And Interpret

Unlock access to all the studying documents.

View Full Document

9-12 Chapter 9 Confidence Intervals and Hypothesis Tests for Means

Quiz B 9-13

9-14 Chapter 9 Confidence Intervals and Hypothesis Tests for Means

Quiz C 9-15

Chapter 9: Sampling Distributions and Confidence Intervals for Proportions – Quiz C

Multiple Choice

Name ________________________________________

9.2.6 Find and interpret confidence intervals.

1. EU (European Union) countries report that 46% of their labor force is female. The

United Nations wants to determine if the percentage of females in the U.S. labor force is

the same. Representatives from the United States Department of Labor select a random

sample of 525 from over 10,000 employment records on file and find that 229 are female.

The 90% confidence interval for the proportion of females in the U.S. labor force is

A. 0.3998 to 0.4722

B. 0.2747 to 0.5973

C. 0.1776 to 0.6944

D. 0.4235 to 0.5679

E. 0.1243 to 0.7100

9.2.6 Find and interpret confidence intervals.

2. EU (European Union) countries report that 46% of their labor force is female. The

United Nations wants to determine if the percentage of females in the U.S. labor force is

the same. Based on a sample of 500 employment records, representatives from the

United States Department of Labor find that the 95% confidence interval for the

proportion of females in the U.S. labor force is .357 to .443. Which of the following is the

correct interpretation?

A. The percentage of females in the U.S. labor force is between 35.7% and 44.3%.

B. We are 95% confident that between 35.7% and 44.3% of the persons in the U.S. labor

force is female.

C. The margin of error for the true percentage of females in the U.S. labor force is

between 35.7% and 44.3%.

D. All samples of size 500 will yield a percentage of females in the U.S. labor force that

falls within 35.7% and 44.3%.

E. None of the above.

9.2.6 Find and interpret margins of error.

3. EU (European Union) countries report that 46% of their labor force is female. The

United Nations wants to determine if the percentage of females in the U.S. labor force is

the same. Based on a sample of 500 employment records, representatives from the

United States Department of Labor find that 240 are female. What is the margin of error

for the 95% confidence interval of the proportion of females in the U.S. labor force?

A. 0.022

B. 0.044

C. 0.036

D. 0.056

E. 0.089

9-16 Chapter 9 Sampling Distributions and Confidence Intervals for Proportions

9.2.7 Find and interpret confidence intervals.

4. EU (European Union) countries report that 46% of their labor force is female. The

United Nations wants to determine if the percentage of females in the U.S. labor force is

the same. Based on a sample of 500 employment records, representatives from the

United States Department of Labor find that the 95% confidence interval for the

proportion of females in the U.S. labor force is .357 to .443. If the Department of Labor

wishes to tighten its interval, they should

A. increase the confidence level.

B. decrease the sample size.

C. increase the sample size.

D. Both A and B

E. Both A and C

9.2.6 Check that inference conditions are satisfied.

5. All else being equal, increasing the level of confidence desired will

A. tighten the confidence interval.

B. decrease the margin of error.

C. increase precision.

D. increase the margin of error.

E. Both A and D.

9.2.6 Check that inference conditions are satisfied.

6. Which of the following is not an assumption and/or condition required for

constructing a confidence interval for the proportion?

A. Randomization condition

B. Linearity condition

C. Success/Failure condition

D. 10% condition

E. None of the above

9.2.6 Find and interpret margins of error.

7. Automobile mechanics conduct diagnostic tests on 150 new cars of particular make

and model to determine the extent to which they are affected by a recent recall due to

faulty catalytic converters. They find that 42 of the new cars tested do have faulty

catalytic converters. What is the margin of error for a 99% confidence interval based on

these sample results?

A. 0.0366

B. 0.0719

C. 0.0944

D. 0.1140

E. 0.2876

Quiz C 9-17

9.2.7 Find and interpret confidence intervals.

8. Automobile mechanics conduct diagnostic tests on 150 new cars of particular make

and model to determine the extent to which they are affected by a recent recall due to

faulty catalytic converters. They find that 42 of the new cars tested do have faulty

catalytic converters. The 99% confidence interval for the true proportion of new cars

with faulty catalytic converters is

A. 0.1856 to 0.3744

B. 0.2434 to 0.3166

C. 0.2081 to 0.3519

D. 0.1660 to 0.3940

E. 0.1243 to 0.4123

9.4.8 Find sample sizes.

9. The U.S. Department of Labor wants to estimate the percentage of females in the labor

force to within ±5% with 90% confidence. As a planning value they use 46%, the

reported percentage of females in the labor force of EU (European Union) countries.

How many employment records should be sampled?

A. 121

B. 269

C. 451

D. 382

E. 1000

9.4.8 Find sample sizes.

10. The U.S. Department of Labor wants to estimate the percentage of females in the

labor force to within ±2% with 90% confidence. As a planning value they use 46%, the

reported percentage of females in the labor force of EU (European Union) countries.

How many employment records should be sampled?

A. 121

B. 269

C. 451

D. 382

E. 1681

9-18 Chapter 9 Sampling Distributions and Confidence Intervals for Proportions

Chapter 9: Confidence Intervals and Hypothesis Tests for Means – Quiz C – Key

Quiz D 9-19

Chapter 9: Sampling Distributions and Confidence Intervals for Proportions – Quiz D

Multiple Choice

Name ________________________________________

9.2.7 Find and interpret confidence intervals.

1. A recent poll of 120 adults who frequent the local farmer’s market found that 54 have

purchased reusable cloth bags for their groceries. The 95% confidence interval for the

proportion of adults who have purchased reusable cloth bags is

A. 0.361 to 0.539

B. 0.4046 to 0.4954

C. 0.4383 to 0.4617

D. 0.205 to 0.525

E. 0.3856 to 0.4896

9.2.6 Find and interpret margins of error.

2. A recent poll of 120 adults who frequent the local farmer’s market found that 54 have

purchased reusable cloth bags for their groceries. Based on these data, what is the margin

of error for a 95% confidence interval of the proportion of adults who have purchased

reusable cloth bags?

A. 0.0454

B. 0.0117

C. 0.089

D. 0.075

E. 0.0432

9.2.7 Find and interpret confidence intervals.

3. One division of a large defense contractor manufactures telecommunication

equipment for the military. This division reports that 12% of non-electrical components

are reworked. Management wants to determine if this percentage is the same as the

percentage rework for the company’s electrical components. Based on a random sample

of 450 electrical components, they find that 46 had to be reworked. The 99% confidence

interval is

A. 0.0652, 0.1388

B. 0.0432, 0.1608

C. 0.0763, 0.1277

D. 0.0541, 0.1499

E. None of the above.

9-20 Chapter 9 Sampling Distributions and Confidence Intervals for Proportions

9.2.7 Find and interpret confidence intervals.

4. One division of a large defense contractor manufactures telecommunication

equipment for the military. This division reports that 12% of non-electrical components

are reworked. Management wants to determine if this percentage is the same as the

percentage rework for the company’s electrical components. The Quality Control

Department plans to check a random sample of the over 10,000 electrical components

manufactured across all divisions. The resulting 95% confidence interval based on these

data is .0758 to .1339. Which of the following is the correct interpretation?

A. The percentage of electronic components that are reworked is between 7.6% and

13.4%.

B. We are 95% confident that between 7.6% and 13.4% of electrical components are

reworked.

C. The margin of error for the true percentage of electrical components that are

reworked is between 7.6% and 13.4%.

D. All samples of size 450 will yield a percentage of reworked electrical components

that falls within 7.6% and 13.4%.

E. None of the above.

9.2.7 Find and interpret confidence intervals.

5. One division of a large defense contractor manufactures telecommunication

equipment for the military. This division reports that 12% of non-electrical components

are reworked. Management wants to determine if this percentage is the same as the

percentage rework for the company’s electrical components. The Quality Control

Department plans to check a random sample of the over 10,000 electrical components

manufactured across all divisions. The 95% confidence interval based on this data is

.0758 to .1339. Should management conclude that the percentage of rework for

electrical components is lower than the rate of 12% for non-electrical components?

A. Yes, because the lower limit of the confidence interval is 7.6%.

B. Yes, because 12% is contained with the 95% confidence interval.

C. No, because 12% is contained with the 95% confidence interval.

D. No, because the upper limit of the confidence interval is 13.4%.

E. None of the above.

9.4.8 Find sample sizes.

6. The Quality Control Department wants to estimate the true percentage of rework for

electrical components to within ±4%, with 99% confidence. Based on similar past

studies, the percentage of rework was found to be 12%. How many components should

they sample?

A. 651

B. 1000

C. 344

D. 438

E. 579

Quiz D 9-21

9.4.8 Find sample sizes.

7. The unemployment rate of persons with a disability is typically higher than for those

with no disability. Recent statistics report that the national rate of unemployment among

this group is 14.5%. The local government of a small city wants to determine the rate in

its region to within ±5%, with 90% confidence. How many individuals with disabilities

should they sample?

A. 135

B. 191

C. 354

D. 678

E. 981

9.4.8 Find sample sizes.

8. The unemployment rate of persons with a disability is typically higher than for those

with no disability. Recent statistics report that the national rate of unemployment among

this group is 14.5%. The local government of a small city wants to determine the rate in

its region to within ±5%, with 95% confidence. How many individuals with disabilities

should they sample?

A. 135

B. 191

C. 354

D. 678

E. 981

9.2.6 Find and interpret margins of error.

9. All else being equal, decreasing the level of confidence desired will

A. widen the confidence interval.

B. increase the margin of error.

C. increase certainty.

D. decrease the margin of error.

E. Both A and B.

9.2.7 Find and interpret confidence intervals.

10. Recent statistics report that the national rate of unemployment among persons with

disabilities is 14.5%. The local government of a small city samples 200 individuals with

disabilities and finds that 44 are unemployed. The 99% confidence interval for the

unemployment rate among persons with disabilities in their city is

A. 0.1646 to 0.2754

B. 0.1735 to 0.2665

C. 0.1446 to 0.2954

D. 0.1332 to 0.3298

E. 0.1145 to 0.4374

9-22 Chapter 9 Sampling Distributions and Confidence Intervals for Proportions

Chapter 9: Confidence Intervals for Proportions – Quiz D – Key