2013_final - Final Exam Instructor Tessa Childers-Day Stat...

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Stat 20Final ExamInstructor: Tessa Childers-Day15 August 2013Please write your name and student ID below, and circle your section. With yoursignature, you certify that you have not observed poor or dishonest conduct on the part ofyour classmates. You also certify that you have not been a party to poor or dishonestconduct, and that the work on this exam is solely your own.Name:Student ID:Signature:Date:Section:102 (3pm-4pm)101 (4pm-5pm)Answer the questions in the spaces provided. There are questions on the front and back ofeach page. This exam has 7 questions, for a total of 75 points and 9 bonus points. Thisfinal is cumulative. Show your work, including labeling quantities (such as z-scores). Theclearer that your work is, the easier it is to award partial or full credit. If you do not showyour work, you will not receive credit. You are welcome to leave your answers as fractions.If you use decimals, please round all answers to two significant figures, and hold yourrounding until the final calculation.QuestionPointsScore111213312412514613Bonus0Total:75
Stat 20Final Exam, Page 2 of 1415 August 20131. A scientist is interested in exploring the relationship between time spent watching television (in minutes)and internet usage (in minutes), each week. She wishes to complete a study on this subject.(a) (2 points) She has the funding to either administer a survey asking 500 participants to self-reporttheir internet and television usage, or to give 250 participants devices which measure their televisionand internet usage and report it to her. Which option would you recommend? Or are they bothequivalent? Explain.After completing the study, the scientist discovers that her subjects spend an average of 400 minper week watching television, with an sd of 100 min, a minimum of 60 min, and a maximum of 900min. They also spend an average of 850 min per week on the internet, with an sd of 175 min, aminimum of 60 min, and a maximum of 1500 min. A scatterplot of the two variables is footballshaped, with a correlation of 0.28.(b) (2 points) If a subject spends 200 minutes per week watching television, predict how much timethey spend on the internet each week. Be sure to include units.(c) (2 points) About how far off is your prediction in part (b) likely to be? Be sure to include units.
Stat 20Final Exam, Page 3 of 1415 August 2013

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