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Unformatted text preview: SOLUTIONS MAT 167: Statistics Test II Instructor: Anthony Tanbakuchi Fall 2008 Name: Computer / Seat Number: No books, notes, or friends. Show your work. You may use the attached equation sheet, R, and a calculator. No other materials. If you choose to use R, write what you typed on the test or copy and paste your work into a word document labeling the question number it corresponds to. When you are done with the test print out the document. Be sure to save often on a memory stick just in case. Using any other program or having any other documents open on the computer will constitute cheating. You have until the end of class to finish the exam, manage your time wisely. If something is unclear quietly come up and ask me. If the question is legitimate I will inform the whole class. Express all final answers to 3 significant digits. Probabilities should be given as a decimal number unless a percent is requested. Circle final answers, ambiguous or multiple answers will not be accepted. Show steps where appropriate. The exam consists of 18 questions for a total of 70 points on 11 pages. This Exam is being given under the guidelines of our institution’s Code of Academic Ethics . You are expected to respect those guidelines. Points Earned: out of 70 total points Exam Score: MAT 167: Statistics, Test II SOLUTIONS p. 1 of 11 Solution: Fall 2008 results. > summary( score ) Min . 1 st Qu. Median Mean 3rd Qu. Max. 65.71 74.29 78.93 80.24 90.18 92.86 > par (mfrow = c (1 , 2)) > boxplot ( score , main = ”Boxplot of exam scores ”) > hist ( score , main = ”Histogram of exam scores ”) 65 70 75 80 85 90 Boxplot of exam scores Histogram of exam scores score Frequency 65 70 75 80 85 90 95 1 2 3 4 1. (1 point) Why is it important to use random sampling? Solution: To prevent bias. Most statistical methods assume random sampling therefore the results will only be reliable if we ensure the assumptions are valid. 2. For the following statements, determine if the calculation requires the use of a population distribution or a sampling distribution . (a) (1 point) Computing a confidence interval for a mean. Solution: Sampling distribution. We need to utilize the distribution of the sample means. (b) (1 point) Determining a pvalue for a one sample proportion hypothesis test. Solution: Sampling distribution. We need to utilize the distribution of the sample statistic. (c) (1 point) Calculating the probability than an individual weights more than 100 lbs. Solution: Population distribution. We need to utilize the distribution of individual’s weights (the population). Instructor: Anthony Tanbakuchi Points earned: / 4 points MAT 167: Statistics, Test II SOLUTIONS p. 2 of 11 (d) (1 point) Computing an interval that contain 95% of individual’s weights....
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 Spring '11
 Tanbakuchi
 Statistics, Normal Distribution, Anthony Tanbakuchi

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