Exam 11: Confidence Intervals for Proportions

Check assumptions / conditions for confidence intervals. -Which of the following is not an assumption and / or condition required for Constructing a confidence interval for the proportion?

Find the sample size. -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?

Find and interpret the confidence interval. -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

Find and interpret the margin of error. -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?

Find and interpret the confidence interval. -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?

Find and interpret the confidence interval. -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

Should representatives from the Department of Labor conclude that the percentage of females in the U.S. labor force is lower than Europe's rate of 46%? Explain.

Find and interpret the margin of error. -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?

Find the sample size. -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?

Are the assumptions and conditions for constructing a confidence interval met? Explain.

Find and interpret the confidence interval. -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?

Find the sample size. -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?

Find and interpret the margin of error. -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

Find and interpret the confidence interval. -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

Find and interpret the confidence interval. -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?

Interpret the confidence interval in this context.

Explain what 99% confidence means in this context.

Find and interpret the margin of error. -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?

They actually select a random sample of 450 electrical components and find that 46 of those had to be reworked. Create the confidence interval.

Are the assumptions and conditions for constructing a confidence interval met? Explain.