Chapter 13 Page 1 of 4 WebQuizzing – Ch. 13 Book ISBN-10 0538477490 Book ISBN-13 9780538477499 Author: Gerald Keller Title: Statistics for Management and Economics Ed: 9e 1. The ratio of two independent chi-squared variables divided by their degrees of freedom is: A. normally distributed. B. Student t distributed. C. chi-squared distributed. D. F-distributed. Analysis: A. Incorrect. The ratio of two independent chi-squared variables divided by their degrees of freedom is F-distributed. B. Incorrect. The ratio of two independent chi-squared variables divided by their degrees of freedom is F-distributed. C. Incorrect. The ratio of two independent chi-squared variables divided by their degrees of freedom is F-distributed. D. Correct. The ratio of two independent chi-squared variables divided by their degrees of freedom is F-distributed. ANSWER: D Ref: Section 13.4 2. The F-distribution is the sampling distribution of the ratio of: A. two normal population variances. B. two normal population means. C. two sample variances . D. None of these choices. Analysis: A. Incorrect. The F-distribution is the sampling distribution of the ratio of two sample variances. B. Incorrect. The F-distribution is the sampling distribution of the ratio of two sample variances. C. Correct. The F-distribution is the sampling distribution of the ratio of two sample variances. D. Incorrect. The F-distribution is the sampling distribution of the ratio of two sample variances. ANSWER: C Ref: Section 13.4 3. Which of the following statements is false for an F-distribution? A. Variables that are F distributed range from 0 to . B. The exact shape of the distribution is determined by two numbers of degrees of freedom. C. The degrees of freedom for the numerator can be larger than, smaller than, or equal to the degrees of freedom for the denominator. D. All of these choices are true. Analysis: Chapter 13 Page 2 of 4 A. Incorrect. All of these choices are true. B. Incorrect. All of these choices are true. C. Incorrect. All of these choices are true. D. Correct. All of these choices are true. ANSWER: D Ref: Section 13.4 4. The sampling distribution of the ratio of two sample variances s12 / s 22 is said to be F distributed provided that: A. the samples are independent from any distributions. B. the populations are normal with equal variances. C. the samples are matched and their sizes are large. D. the samples are independently drawn from two normal populations. Analysis: A. Incorrect. Provided that the samples are independently drawn from two normal populations. B. Incorrect. Provided that the samples are independently drawn from two normal populations. C. Incorrect. Provided that the samples are independently drawn from two normal populations. D. Correct. Provided that the samples are independently drawn from two normal populations. ANSWER: D Ref: Section 13.4 5. Two independent samples are drawn from two normal populations, where the population variances are assumed to be equal. The sampling distribution of the ratio of the two sample variances is: A. normal B. Student-t C. F D. chi-squared Analysis: A. Incorrect. The sampling distribution of the ratio of the two sample variances is F B. Incorrect. The sampling distribution of the ratio of the two sample variances is F C. Correct. The sampling distribution of the ratio of the two sample variances is F D. Incorrect. The sampling distribution of the ratio of the two sample variances is F ANSWER: C Ref: Section 13.4 6. The test for the equality of two population variances is based on the: A. difference between the two sample variances. B. ratio of the two sample variances. C. sum of the two sample variances. D. product of the two sample variances. Analysis: A. Incorrect. The test for the equality of two population variances is based on the ratio of the two sample variances. Chapter 13 Page 3 of 4 B. Correct. The test for the equality of two population variances is based on the ratio of the two sample variances. C. Incorrect. The test for the equality of two population variances is based on the ratio of the two sample variances. D. Incorrect. The test for the equality of two population variances is based on the ratio of the two sample variances. ANSWER B Ref: SECTION 13.4 7. In constructing a confidence interval estimate for the difference between two population proportions, we: A. pool the population proportions when the populations are normally distributed. B. pool the population proportions when the population means are equal. C. pool the population proportions when they are equal. D. never pool the population proportions. Analysis: A. Incorrect. We never pool the population proportions. B. Incorrect. We never pool the population proportions. C. Incorrect. We never pool the population proportions. D. Correct. We never pool the population proportions. ANSWER: D Ref: Section 13.5 8. For testing the difference between two population proportions, the pooled proportion estimate should be used to compute the value of the test statistic when the: A. populations are normally distributed. B. sample sizes are small. C. samples are independently drawn from the populations. D. null hypothesis states that the two population proportions are equal. Analysis: A. Incorrect. When the null hypothesis states that the two population proportions are equal. B. Incorrect. When the null hypothesis states that the two population proportions are equal. C. Incorrect. When the null hypothesis states that the two population proportions are equal. D. Correct. When the null hypothesis states that the two population proportions are equal. ANSWER: D Ref: Section 13.5 9. The pooled proportion estimate is used when: A. the proportion of successes from sample 1 equals the proportion of successes from sample 2. B. the total number of successes in both samples divided by the total of both sample sizes equals 1. C. the null hypothesis states that the two population proportions differ by some non-zero number. D. None of these choices. Analysis: Chapter 13 Page 4 of 4 A. Incorrect. None of these choices. B. Incorrect. None of these choices. C. Incorrect. None of these choices. D. Correct. None of these choices. ANSWER: D Ref: Section 13.5

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