# econ203 8-18 - Question#1 This question is identical to...

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Question #1 This question is identical to example #1 on slide 26 (page 57) of your course packet. To determine whether a new steel-belted radial tires lasts longer than an existing model, Firestone designs the following experiment. One tire of each type (an existing model and an old model) were installed on the rear wheels of 20 randomly selected cars. The number of miles driven by each driver, until tires wore out, were recorded and are stored here . Hint: first think about whether the two samples are independent or dependent. What is the relevant point estimate? 73.6-69.05 = 4.55 What is the value of the test statistic? 2.817586929 What is the p-value for this test? 0.005496978 Allowing for a 5% chance of a Type I error, what is your conclusion for this test? Reject the null hypothesis and conclude that new tires last longer. Do not reject the null hypothesis and conclude that new tires last longer. Reject the null hypothesis and conclude there is not enough evidence to claim that new tires last longer. Do not reject the null hypothesis and conclude there is not enough evidence to claim that new tires last longer. Now create a 95% confidence interval for the difference in means of the two populations. The lower and upper bounds are 4.592 and <no answer> respectively. You received a raw score of 67% on this question. Question #2 This question is the same as example #2 on slide 30 (page 58) of the course packet. In an agricultural experiment, two expensive high-yield varieties of corn are to be tested and yield improvements are to be measured. The experiment is arranged so that each variety is planted in ten pairs of similar plots. Data is collected on yield increases obtained for these two varieties. Plot Variety Variety

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A B 1 12.6 10.5 2 9.2 8.1 3 6.4 6.2 4 9.8 10.1 5 15.3 12.2 6 16.1 14 7 12.3 10.1 8 11.3 13.6 9 12.2 9.8 10 14.1 13.4 Which of the following tests should be used? A pooled variance t-test should be used since we have independent samples. A paired sample t-test should be used since we have independent samples. An unequal variance t-test should be used because even though we have independent samples, the sample variances appear to be rather different. A paired sample t-test should be used since we have dependent samples. A pooled variance t-test should be used since we have dependent samples. Which of the following statements is true about the test statistic for this test? The calculated test statistic is 2.217 The calculated test statistic is 2.093. The calculated test statistic is 1.201. The calculated test statistic is 1.899. The calculated test statistic is 1.729. The calculated test statistic is 1.796. Using a 5% level of significance, and testing if mean yields are DIFFERENT, which of
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## This note was uploaded on 07/23/2010 for the course ECON 203 taught by Professor Petry during the Spring '08 term at University of Illinois at Urbana–Champaign.

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econ203 8-18 - Question#1 This question is identical to...

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