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Unformatted text preview: Midterm 1  Spring 2010  Form A Economics 203 Instructors: Petry and Sahakyan Name: Before beginning the exam, please verify that you have 15 pages with 43 questions in your exam booklet. You should also have a decisiontree and formula sheet provided to you. Please include your full name and NetID on your bubble sheets. Based on the name of your TA and discussion time, please code in the following for the “Section” portion on your scantron: TA Name Discussion Day and Time Section Josh Brown Thursday 9am 001 Josh Brown Thursday 10am 002 Josh Brown Thursday 11am 003 Rafael Ribas Thursday 12pm 004 Rafael Ribas Thursday 1pm 005 Rafael Ribas Thursday 2pm 006 Andreas Hagemann Friday 8am 007 Andreas Hagemann Friday 9am 008 Andreas Hagemann Friday 10am 009 Sergey Popov Friday 11am 010 Sergey Popov Friday 12pm 011 Sergey Popov Friday 1pm 012 Esra Ergul Friday 11am 013 Esra Ergul Friday 12pm 014 Esra Ergul Friday 1pm 015 Lusha Zhu Friday 2pm 016 Lusha Zhu Friday 3pm 017 Lusha Zhu Friday 4pm 018 Good luck! 1. Which of the following is a measure of central tendency? a. Median b. Standard Deviation c. Proportion d. Covariance e. Regression 2. The number of employees per store employed by a certain donut franchise is approximately normally dis tributed with a mean of 23 and standard deviation of 4. Approximately what percentage of stores will have between 19 and 31 employees? a. 68% b. 81.5% c. 84% d. 95% e. 97.5% 1 Use the following information to answer the next 2 questions (34): After implementing the latest round of quality control measures, your company would like to know if the widgets they produce have become more consistent in size. Achieving the same average length has never been a problem; but the lengths were always quite variable before, with a variance of 7.4. In a random sample of 50 widgets after the changes, the sample variance is 5.1. 3. What are your null and alternative hypotheses? a. H : σ 2 ≥ 5 . 1 vs. H 1 : σ 2 < 5 . 1 b. H : σ 2 ≥ 7 . 4 vs. H 1 : σ 2 ≤ 7 . 4 c. H : σ 2 ≥ 7 . 4 vs. H 1 : σ 2 < 5 . 1 d. H : σ 2 = 7 . 4 vs. H 1 : σ 2 = 5 . 1 e. H : σ 2 = 7 . 4 vs. H 1 : σ 2 < 7 . 4 4. What is the value of the test statistic for the previous problem? a. 23.274 b. 23.749 c. 33.770 d. 34.459 e. 71.098 5. You read in a magazine that men are on average five inches taller than women. You think that the difference is greater than this in your hometown. You sample 14 men (population 1) and 17 women (population 2) from your hometown; the men average 71 inches, and the women average 64.5 inches. The magazine article also told you that the standard deviations for men and women are 4 and 3 inches respectively. What is the value of the test statistic for your hypothesis?...
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 Spring '09
 PETRY
 Economics, Variance, Null hypothesis

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