Template binomial problems_stud

Template binomial problems_stud - Template binomial...

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// See handout #6a 03/19/10 Problem #11. Find the expected value of µ and the variance σ 2 for the following random variable x . i x i P(x i ) x i *P(x i ) x i 2 x i 2 *P(x i ) 1 9 0.14 2 12 0.22 3 15 0.36 4 18 0.18 5 21 0.1 The mean µ = Σ = The variance σ 2 = Σ – µ 2 = Problem 3 . Let us consider the following probability experiment. A six-question multiple choice test is to be given. A student has not studied the material to be tested and therefore decides to answer the six questions by randomly guessing the answers without reading the questions or the answers. The answer page to test is as follows. Directions: Circle the best answer to each question. 1. A B C 3. A B C 5. A B C 2. A B C 4. A B C 6. A B C (Circle your answers before counting) Solution. Before we look at the correct answers to the test, let us think about some questions which might arise when a test is answered in this way. 1. What is the probability that a student selected wrong answers to all six questions? 2. What is the probability that a student selected correct answers to all six questions? 3. What is the most likely number of correct answers? This is the binomial probability problem ; the answering to a question is a trial with two possible outcomes: correct answer and wrong answer. These outcomes are not equally likely: the probability of correct answer is p = 1/3 , and the probability of wrong answer is 1 – p = 2/3. The number of trials n = 6 (six questions). 1
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Template binomial problems_stud - Template binomial...

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