Sample Midterm2

Sample Midterm2 - Stat 31.xx Midterm 2 Name (please print):...

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Stat 31.xx Midterm 2 Name (please print): INSTRUCTIONS: 1. Answer all questions and show all work on the exam in the space provided. Please be free to use the back pages if necessary. You will not receive credit if you do not justify your answers. 2. Circle your final answers. 3. Remember to sign the Honor Pledge below. I pledge that I have neither given nor received unauthorized assistance during this examination. Signed: ----------------------------------------------------------------------
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1. (x points) What is the preferred treatment for breast cancer that is detected in its early stages? The most common treatment was once mastectomy (removal of the breast). It is now usual to remove the tumor and nearby lymph nodes, followed by radiation. To study whether these treatments differ in their effectiveness, a medical team examines the records of 25 large hospitals and compares the survival times after surgery of all women who have had either treatment. (a) What are the explanatory and response variables? (b) Explain carefully why this study is not an experiment. (c) Do you think this study will show whether a mastectomy causes longer average survival time? Explain your answer carefully. 2. (x points) We know that ) 6 . 0 , 40 ( ~ B X and ) 1 , 8 ( ~ N Y . Let 4 3 2 + + = Y X Z . Assuming independence between the random variables X and Y, (a) Find the mean Z μ of Z. (b) Find the standard deviation Z σ of Z. 2
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3. (x points) A medical study of heart surgery investigates the effect of drugs called beta-blockers on the pulse rate of the patient during surgery. The pulse rate will be measured at a specific point during the operation. The investigators decide to use as subjects 30 patients facing heart surgery who have consented to take part in the study. You have a list of these patients, numbered up to 30 in alphabetical order.
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This note was uploaded on 03/30/2008 for the course STAT 31 taught by Professor Unknown during the Summer '07 term at UNC.

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Sample Midterm2 - Stat 31.xx Midterm 2 Name (please print):...

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