Econ 203 Hmwk 7 - Graded Homework 7 You have submitted this...

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Graded Homework 7 You have submitted this Homework 6 times (including this time). You may submit this Homework a total of 40 times and receive full credit. The first three questions cover tests for the difference between means in dependent samples, material that can be found in your course packet on pages 57-58. The last five questions are about tests for the difference between two population proportions, whether the null hypothesis is that the proportions are equal or not. This material can be found on pages 58-61 in your course packet. 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? 4.55 What is the value of the test statistic? 2.817586964 What is the p-value for this test? 0.00549698 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. 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. Do not reject the null hypothesis and conclude 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 1.17 and 7.93 respectively. Item 5: Your answer is within ±.0001 of the solution - correct. Item 6: Your answer is within ±.0001 of the solution - correct.
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You received a raw score of 100% 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 A Variety 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 dependent samples. A paired sample t-test should be used since we have dependent samples. An unequal variance t-test should be used because even though we have
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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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Econ 203 Hmwk 7 - Graded Homework 7 You have submitted this...

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