CP Stats Ch 8 Review

• We are confident that 95% of all young women have BMI between 26.2 and 27.4

• We are 95% confident that future samples of young women will have mean BMI between 26.2 and 27.4

• Any value from 26.2 to 27.4 is believable as the true mean BMI of young American women

• If we take many samples, the population mean BMI will be between 26.2 and 27.4 in about 95% of those samples

• The mean BMI of young American women cannot be 28.

The admissions director from Big City University found that (107.8, 116.2) is a 95% confidence interval for the mean IQ score of all freshman. Select all correct answers (hint: 2 are correct)

• There is a 95% probability that the interval from 107.8 to 116.2 contains

• There is a 95% chance that the interval (107.8, 116.2) contains x-bar

• This interval was constructed using a method that produces intervals that capture the true mean 95% of the time

• If we take many samples, about 95% of them will contain the interval (107.8, 116.2)

A researcher plans to use a random sample of families to estimate the mean monthly income for a large population. This researcher is deciding between a 95% and 99% confidence level. Compared to a 95% confidence interval, a 99% confidence interval will be...

• Narrower and involve a larger risk of being incorrect

• Wider and would involve a smaller risk of being incorrect

• Narrower and would involve a smaller risk of being incorrect

• Wider and would involve a larger risk of being incorrect

• Wider and would have the same risk of being incorrect

A researcher plans to use a random sample of families to estimate the mean monthly income for a large population.

The researcher is deciding between a sample of size n=500 and n=1000. Compared to using a sample size of n=500, a 95% confidence interval based on a sample of size n=1000 will be...

• Narrower and involve a larger risk of being incorrect

• Wider and would involve a smaller risk of being incorrect

• Narrower and would involve a smaller risk of being incorrect

• Wider and would involve a larger risk of being incorrect

• Narrower and would have the same risk of being incorrect

You have measured to systolic blood pressure of an SRS of 25 company employees. A 95% confidence interval for the mean systolic blood pressure for the employees of this company is (122, 138). Which of the following statements is true?

• 95% of the sample of employees have a systolic blood pressure between 122 and 138

• 95% of the population of employees have a systolic blood pressure between 122 and 128

• If the procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure

• If the procedure were repeated many times, 95% of the time the population mean systolic blood pressure would be between 122 and 138

• If the procedure was repeated many times, 95% of the time the sample mean systolic blood pressure would be between 122 and 138

• The poll used a method that gets an answer within 3% points of the truth about the population 95% of the time

• The percent of all adults who expect an inheritance is between 25% and 31%

• if Gallup takes another poll on this issue, the results of the second poll will lie between 25% and 31%

• There's a 95% chance that the percent of all adults who expect an inheritance is between 25% and 31%

• Gallup can be 95% confident that between 25% and 31% of the sample expect an inheritance

Most people can roll their tongues, but many can't. The ability to roll the tongue is genetically determined. Suppose we are interested in determining what proportion of students can roll their tongues. We test an SRS of 400 students and find that 317 can roll their tongues. The MOE for a 95% confidence interval for the true proportion of tongue rollers among students is...

• 0.0008

• 0.02

• 0.03

• 0.04

• 0.05

You want to design a study to estimate the proportion of students at your school who agree with the statement, "The student government is an effective organization for expressing the needs of students to the administration." You will use a 95% confidence interval, and you would like the MOE to be 0.05 or less. The minimum sample size required is...

• 22

• 271

• 385

• 769

• 1795

A newspaper reporter asked an SRS of 100 residents in a large city for their opinion about the mayor's job performance. Using the results from the sample, the C% confidence interval for the proportion of all residents in the city who approve of the mayor's job performance is 0.565 to 0.695. What is the value of C?

• 82

• 86

• 90

• 95

• 99

You have an SRS of 20 observations from a large population. The distribution of sample values is roughly symmetric with no outliers. What critical value would you use to obtain a 98% confidence interval for the mean of the population?

• 2.177

• 2.183

• 2.326

• 2.500

• 2.508