EXS_EX.2.2008Spring

EXS_EX.2.2008Spring - SOLUTIONS MAT 167: Statistics Test II...

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Unformatted text preview: SOLUTIONS MAT 167: Statistics Test II Instructor: Anthony Tanbakuchi Spring 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 13 questions for a total of 84 points on 12 pages. This Exam is being given under the guidelines of our institutions Code of Academic Ethics . You are expected to respect those guidelines. Points Earned: out of 84 total points Exam Score: MAT 167: Statistics, Test II SOLUTIONS p. 1 of 12 Solution: Spring 2008 results. I made the exam out of 82 points instead of 84. > summary( score ) Min . 1 st Qu. Median Mean 3rd Qu. Max. 43.29 68.60 81.10 75.75 89.79 95.12 > par (mfrow = c (1 , 2)) > boxplot ( score , main = Boxplot of exam scores ) > hist ( score , main = Histogram of exam scores ) 50 60 70 80 90 Boxplot of exam scores Histogram of exam scores score Frequency 40 50 60 70 80 90 1 2 3 4 5 6 1. An experiment consists of randomly sampling 10 students at Pima Community College, record- ing their heights and computing their mean height. If we repeat the experiment over and over (assume simple random samples, no human errors, no bias) we observe that the sample mean height varies each time. (a) (2 points) What is the name of the error that causes the mean to vary each time? Solution: sampling error (b) (2 points) Explain how it is possible for the sample mean height to vary each time? What is going on? Solution: Each time we conduct a random sample of size n from a fixed population, the elements that are selected in the sample will vary. Since the samples vary then we would expect the sample mean to vary as well. This is the natural variation we would expect to see from sample to sample called sampling error. (c) (2 points) In words, state what the population distribution represents in this experiment. (Be specific.) Solution: A population distribution describes the distribution of population values....
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This note was uploaded on 02/10/2012 for the course MAT 1670 taught by Professor Tanbakuchi during the Spring '11 term at University of Florida.

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EXS_EX.2.2008Spring - SOLUTIONS MAT 167: Statistics Test II...

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