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Final Exam Study Guide

Final Exam Study Guide - df-t Stat-0.32696 P(T<=t...

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MSCI 3710 Paired (dependent) two sample t-test (Chapter 9): Sample Exam Problem 6 Note: The following problem is taken from the Final Exam in Spring 2003,version A, questions 5-7. A recent commercial claims that the international phone call rates offered by IDT are lower than those of MCI. A consumer decided to test this claim by collecting and analyzing data from IDT’s and MCI’s Web sites ( www.idt.net , www.mci.com ). The rates offered by each company, in cents per minute, for international calls from the U.S. to 14 selected countries and their statistical analysis are listed below. Is it true that IDT rates are lower? Country MCI IDT Argentina 19.0 20.0 Brazil 19.0 20.0 Canada 5.0 5.0 China 17.0 16.0 France 12.0 7.0 Germany 12.0 7.0 Greece 12.0 17.3 India 33.0 59.0 Israel 15.0 11.0 Italy 12.0 7.0 Japan 14.0 9.0 Mexico-1 10.0 19.0 Russia 23.0 19.0 U.K. 10.0 7.0 t-Test: Paired Two Sample for Means, alpha = 0.05 MCI IDT Mean 15.21429 15.95 Variance 46.95055 186.12731 Observations 14 14 Pearson Correlation 0.867511 Hypothesized Mean Difference
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Unformatted text preview: df----t Stat-0.32696 P(T<=t) one-tail 0.374452 t Critical one-tail 1.770932 P(T<=t) two-tail 0.748903 t Critical two-tail 2.160368 1. What are the decision and conclusion using a dependent samples t-test if the test is conducted at the 5% significance level? A. There is insufficient information to decide whether IDT rates are lower. B. Fail to reject the null hypothesis, conclude IDT rates are lower. C. Fail to reject the null hypothesis, conclude there is insufficient evidence for IDT rates being lower. D. Reject the null hypothesis, conclude IDT rates are not lower. E. Reject the null hypothesis, conclude IDT rates are lower 2. How many degrees of freedom do we have in the distribution of the test statistic? A. 26 B. 27 C. 13 D. 14 E. 28 3. What is the critical value of the test statistic for this test if the test is conducted at the 5% significance level? A. 1.77 B. 2.16 C. 0.37 D. 0.74 E. 1.645 1...
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