University of California, Los Angeles - STATS 100Amidterm1pspring14-key

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Stat 100A -Intro Probability Practice Midterm 1 J. Sanchez UCLA Department of Statistics MUST DO BEFORE STARTING EXAM (a) WRITE AND MARK YOUR NAME AND ID ON THE SCANTRON (b) WRITE YOUR NAME ON BO... TH SIDES OF THE CHEAT SHEET. (c) DO NOT DETACH ANY PAGES FROM THIS EXAM. EXAM MUST STAY STAPLED DURING THE WHOLE EXAM. (d) Write here your UCLA ID: − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − − −− NO ID NO EXAM. ID MUST BE ON YOUR DESK AT ALL TIMES. AT BEGINNING OF EXAM and THROUGHOUT THE EXAM. (e) Write here your LAST NAME (Please, PRINT): − − − − − − − − − − − − − − − − − − −− FIRST NAME: − − − − − − − − −− Other important Instructions–Read. Points lost for not following directions. • Closed books, closed notes. • Only scientific calculator allowed for computations. You may not use your phone or any other electronic device as calculator. Graphics calculators are not allowed. No exceptions. • Phones and other electronic devices must be disconnected before you enter the classroom and not turn on again until you are out of the room. While in the classroom, they must be in your backpack and your backpack on the floor. Phones in pockets will lead to big loss of points in the exam. It is not worth the risk. • Answer for multiple choice questions will be marked in scantron AND the exam. Work will not be read in multiple choice;Failure to mark your name, ID or some answers will result in point deduction from the exam grade. • Left handed students will sit in a seat for left-handed students. The professor will tell students where to sit. Please, let the professor know that you are left handed ahead of time and she will move you. • ID must be ready to show BEFORE and at all times during the exam. NO ID, no exam. • This midterm must show your individual work. Talking to others during the midterm, not adhering to the above, sharing information or breaking any other aspect of the student code of conduct at UCLA will not be tolerated. You can not exchange papers or information. All your things must be on the floor. You may not use the empty seats next to you to put things. Close the tables. Honor code applies. • Cheat sheet can have only formulas and definitions, no solved problems, no examples of any kind, no proofs, no numerical examples, no intermediate steps and no drawings or graphs of any kind.YOUR NAME MUST BE ON CHEAT SHEET AT ALL TIMES. Be ready to show your cheat sheet when the instructor requests it. The cheat sheet must be written all in English. Cheat sheets that do not comply will result in lower grade in the exam. April 19, 2014 1 Stat 100A -Intro Probability Practice Midterm 1 J. Sanchez UCLA Department of Statistics • Failure to follow instructions given here will result in loss of points in the exam in a first warning and more severe consequences on a second warning. Honor code applies. Familiarize yourself with student code of conduct by visiting the links provided in the course syllabus. NOTE: This practice exam is only an indication of format of the exam. All your exam will be in multiple choice format. A practice midterm is to test yourself. Be aware that the questions in the midterm will be different from the ones in the practice midterm. So studying for the test by studying only the practice midterm is a bad idea. With this midterm, you can test yourself after studying. Look at the answers only when you have done it by yourself. It will give you an indication of how prepared are you to answer new questions. April 19, 2014 2 Stat 100A -Intro Probability Practice Midterm 1 J. Sanchez UCLA Department of Statistics MULTIPLE CHOICE QUESTIONS. ONLY ONE ANSWER IS CORRECT. CHOICE MUST BE MARKED ON THE SCANTRON, AND ALSO HERE ON THE EXAM. ONLY THE SCANTRON WILL BE GRADED. NO MARKS ON SCANTRON OR MORE THAN ONE MARK WILL RESULT IN 0 POINTS FOR THE QUESTION NOT MARKED, EVEN IF IT IS MARKED ON THE EXAM. You may use the space near the question for scratch work, but scratch work will not be read. Question 1. Police report that 78% of drivers stopped on suspicion of drunk driving are given a breath test, 36% a blood test, and 22% both tests. What is the probability that a randomly selected DWI suspect is given a blood test or a breath test, but not both? (a) 0.7 (b) 0.3 (c) 0.08 (d) 0.22 (e) 0.12 Solution 1. P(Bbc ∪ B cb) = (0.78 − 0.22) + (0.36 − 0.22) = 0.56 + 0.14 = 0.7 Question 2. Let S = (0, 1] and define Ai = ((1/i), 1], i = 1, 2, ...... The union of these events is (a) S, the whole sample space. (b) The interval [0, 0.5]. (c) The set with only 1 in it. (d) The empty set. (e) The interval [0, 10] [Show More]

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