sample exam 2 key

sample exam 2 key - First 5 letters of your last name Last...

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First 5 letters of your last name Last 5 digits of your Student Number (SSN) Name: ________________________________________________ l a s t f i r s t M I Instructions: You must use pencil to write your quiz. Turn off all cell phones and pagers. You may not use cell phones or other PDA’s for any purpose during the quiz. Leave the quiz paper UNOPENED until you are instructed to begin. Neatly fill in the requested information above. Probability table(s) will be distributed separate from the exam paper. Do not write on these tables. Return the probability tables with your exam paper. You may not leave the room for any reason before you submit your paper. You may not ask questions during the exam. If you have a concern regarding a question, write a brief note explaining your concern. Circle the best answer to each multiple-choice question. Answer all free-response questions neatly in the spaces provided. You must show all work necessary to answer all questions, including the multiple- choice questions , in order to receive full credit. Do not presume that anything is obvious or too simple to be written down. If you detach your formula page from the exam packet, it must be turned in with your exam. Print your name at the top of the formula page.
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1. (3) Which of the following is not true about the Student’s t - distribution? It is used to construct confidence intervals for the population mean when the population standard deviation is known 2. (2) If you were constructing a 99% confidence interval of the population mean based on a sample of n = 25 where the standard deviation of the sample s = 0.05, the critical value of t will be t .005,24 = 2.797 3. (3) A manger of a small company would like to determine whether the average monthly balance of credit card holders is equal to $120. An auditor selects a random sample of 100 accounts and finds that the average owed is $128.7 with a sample standard deviation of $26.9. If you wanted to test whether the auditor should conclude that there is evidence that the average balance is different from $120, which test would you use? t -test of population mean 4. (8) After a financial analysis, the general manager of a large company decided that if more than 8% of potential buyers of a new product purchase that product, the company would show a profit. A hypothesis test is designed using α = 0.05 and n = 100 for the following hypotheses: H 0 : p 0.08 vs. H 1 : p > 0.08. What is the probability that 10% of potential buyers would actually purchase the product, but the test results in the conclusion that the product will not be profitable? Step 1: Definition of what you need to find: β = P(DNR H 0 / H 1 is true) Step 2: Find the Decision Rule: Reject H0 0.05 = 0.08 + 1.645 p ˆ c p ˆ 100 ) 92 . 0 ( 08 . 0 = 0.1246 0.08 = .1246 c p ˆ Step 3: Rewrite the definition from Step 1 in terms of your decision rule and alternative parameter value. P( 0.1246 / p = 0.10) p ˆ Step 4: Calculate the probability.
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sample exam 2 key - First 5 letters of your last name Last...

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