Exam 11: Inferences About Population Variances

The contents of a sample of 26 cans of apple juice showed a standard deviation of .06 ounces. We are interested in testing whether the variance of the population is significantly more than .003. The test statistic is

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Question 21

Based on the sample evidence below, we want to test the hypothesis that population A has a larger variance than population B. The p-value is approximately

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Question 22

The value of F_.01 with 9 numerator and 20 denominator degrees of freedom is

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Question 23

The 90% confidence interval estimate of a population standard deviation when a sample variance of 50 is obtained from a sample of 15 items is

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Question 24

The 99% confidence interval estimate for a population variance when a sample standard deviation of 12 is obtained from a sample of 10 items is

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Question 25

For a sample size of 21 at 95% confidence, the chi-square values needed for interval estimation are

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Question 26

We are interested in testing whether the variance of a population is significantly less than 1.44. The null hypothesis for this test is

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Question 27

A sample of 51 observations yielded a sample standard deviation of 5. If we want to test H₀: σ² = 20, the test statistic is

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Question 28

We are interested in testing whether the variance of a population is significantly more than 625. The null hypothesis for this test is

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Question 29

Consider the following hypothesis problem. If the test is to be performed at the .05 level of significance, the null hypothesis

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Question 30

For an F distribution, the number of degrees of freedom for the numerator

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Question 31

The manager of the service department of a local car dealership has noted that the service times of a sample of 30 new automobiles has a standard deviation of 5 minutes. A 95% confidence interval estimate for the standard deviation of the service times (in minutes) for all their new automobiles is

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Question 32

A lumber company has claimed that the standard deviation for the lengths of their six-foot boards is .4 inches or less. To test their claim, a random sample of 16 six-foot boards is selected; and it is determined that the variance of the sample is .3. Do the results of the sample support the company's claim? Use α = .1.

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Question 33

In practice, the most frequently encountered hypothesis test about a population variance is a

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Question 34

The critical value of F using α = .05 when there is a sample size of 21 for the sample with the smaller variance, and there is a sample size of 9 for the sample with the larger sample variance is

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Question 35

There is a .90 probability of obtaining a value such that

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Question 36

A sample of 21 elements is selected to estimate a 90% confidence interval for the variance of the population. The chi-square value(s) to be used for this interval estimation is(are)

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Question 37

A random sample of 20 observations showed a standard deviation of 8. At a .05 level of significance, test to see if the variance of the population is significantly less than 65. Use the critical value approach.

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Question 38

The producer of a certain medicine claims that their bottling equipment is very accurate and that the standard deviation of all their filled bottles is .2 ounces or less. A sample of 20 bottles showed a standard deviation of .12 ounces. The test statistic to test the claim is

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Question 39

Student advisors are interested in determining if the variances of the scores of day students and night students are the same. The following samples are drawn: Test the equality of the variances of the populations. Let α = .05.

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Question 40

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Exam 11: Inferences About Population Variances

The contents of a sample of 26 cans of apple juice showed a standard deviation of .06 ounces. We are interested in testing whether the variance of the population is significantly more than .003. The test statistic is

Based on the sample evidence below, we want to test the hypothesis that population A has a larger variance than population B. ​ ​ The p-value is approximately

The value of F.01 with 9 numerator and 20 denominator degrees of freedom is

The 90% confidence interval estimate of a population standard deviation when a sample variance of 50 is obtained from a sample of 15 items is

The 99% confidence interval estimate for a population variance when a sample standard deviation of 12 is obtained from a sample of 10 items is

For a sample size of 21 at 95% confidence, the chi-square values needed for interval estimation are

We are interested in testing whether the variance of a population is significantly less than 1.44. The null hypothesis for this test is

A sample of 51 observations yielded a sample standard deviation of 5. If we want to test H0: σ2 = 20, the test statistic is

We are interested in testing whether the variance of a population is significantly more than 625. The null hypothesis for this test is

Consider the following hypothesis problem. ​ ​ If the test is to be performed at the .05 level of significance, the null hypothesis

For an F distribution, the number of degrees of freedom for the numerator

The manager of the service department of a local car dealership has noted that the service times of a sample of 30 new automobiles has a standard deviation of 5 minutes. A 95% confidence interval estimate for the standard deviation of the service times (in minutes) for all their new automobiles is

​In practice, the most frequently encountered hypothesis test about a population variance is a

The critical value of F using α = .05 when there is a sample size of 21 for the sample with the smaller variance, and there is a sample size of 9 for the sample with the larger sample variance is

There is a .90 probability of obtaining a value such that ​

A sample of 21 elements is selected to estimate a 90% confidence interval for the variance of the population. The chi-square value(s) to be used for this interval estimation is(are)

A random sample of 20 observations showed a standard deviation of 8. At a .05 level of significance, test to see if the variance of the population is significantly less than 65. Use the critical value approach.

The producer of a certain medicine claims that their bottling equipment is very accurate and that the standard deviation of all their filled bottles is .2 ounces or less. A sample of 20 bottles showed a standard deviation of .12 ounces. The test statistic to test the claim is

Student advisors are interested in determining if the variances of the scores of day students and night students are the same. The following samples are drawn: ​ Test the equality of the variances of the populations. Let α = .05.

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

Interval Estimation

Hypothesis Tests

Inference About Means and Proportions With Two Populations

Comparing Multiple Proportions, Tests of Independence and Goodness of Fit

Experimental Design and Analysis of Variance

Simple Linear Regression

Multiple Regression

Regression Analysis: Model Building

Time Series Analysis and Forecasting

Nonparametric Methods

Decision Analysis

Index Numbers

Statistical Methods for Quality Control

Sample Survey

Filters

Based on the sample evidence below, we want to test the hypothesis that population A has a larger variance than population B. The p-value is approximately

The value of F_.01 with 9 numerator and 20 denominator degrees of freedom is

A sample of 51 observations yielded a sample standard deviation of 5. If we want to test H₀: σ² = 20, the test statistic is

Consider the following hypothesis problem. If the test is to be performed at the .05 level of significance, the null hypothesis

In practice, the most frequently encountered hypothesis test about a population variance is a

There is a .90 probability of obtaining a value such that

Student advisors are interested in determining if the variances of the scores of day students and night students are the same. The following samples are drawn: Test the equality of the variances of the populations. Let α = .05.