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.

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CCSS.HSS.IC.B.4

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)

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CCSS.HSS.IC.B.4

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

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CCSS.HSS.IC.B.4

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

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CCSS.HSS.IC.B.4

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

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CCSS.HSS.IC.B.4

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

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CCSS.HSS.IC.B.4

One reason for using a t distribution instead of a standard Normal curve to find critical values when calculating a level C confidence interval for a population mean is that...

• z can only be used for large samples

• z requires that you can regard your data as an SRS from the population

• z requires that the sample size is at most 10% of the population size

• a z critical value will lead to a wider interval than a t critical value

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CCSS.HSS.ID.A.4

• 90% confidence; n=25

• 90% confidence; n=50

• 95% confidence; n=25

• 95% confidence; n=50

• n=100 at any confidence level

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CCSS.HSS.IC.B.4

• There is a clear outlier in the data

• The stemplot of the data shows a mild right skew

• The population distribution is not exactly Normal

• None of these are a problem when using a t interval

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CCSS.HSS.IC.B.4