# CH13 - 13: INFERENCE ABOUT COMPARING TWO POPULATIONS...

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Unformatted text preview: 13: INFERENCE ABOUT COMPARING TWO POPULATIONS MULTIPLE CHOICE QUESTIONS In the following multiple-choice questions, please circle the correct answer. 1. 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. a normal distribution b. Student t distribution c. an F distribution d. a chi-squared distribution ANSWER: c 2. The expected value of the difference of two sample means equals the difference of the corresponding population means: a. only if the populations are normally distributed b. only if the samples are independent c. only if the populations are approximately normal and the sample sizes are large d. the statement is correct under all circumstances ANSWER: d 3. In constructing 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 ANSWER: d 4. In constructing 95% confidence interval estimate for the difference between the means of two normally distributed populations, where the unknown population variances are assumed not to be equal, summary statistics computed from two independent samples are as follows: 50 1 = n 175 1 = x 5 . 18 1 = s 42 2 = n 158 2 = x 4 . 32 2 = s The upper confidence limit is: a. 19.123 b. 28.212 c. 24.911 d. 5.788 ANSWER: b 5. 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 ANSWER: d 6. A sample of size 100 selected from one population has 60 successes, and a sample of size 150 selected from a second population has 95 successes. The test statistic for testing the equality of the population proportions equal to: a.-0.5319 b. 0.7293 c.-0.419 d. 0.2702 ANSWER: a 7. 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 ANSWER: d 8. The F distribution is the sampling distribution of the ratio of: a. two normal population variances b. two normal population means c.c....
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## This document was uploaded on 10/25/2011 for the course LAPS 2320 at York University.

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CH13 - 13: INFERENCE ABOUT COMPARING TWO POPULATIONS...

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