Homework 9 (Due date: April 24, 2004 in class)

·  Make sure to write your name and section number on each page clearly. Do not write your SSN or ID.

·  Staple everything together. Place it on the table before class starts. There is a penalty of 5 pt. if you do not staple them together.

·  If you come to class after the lecture has started, do not walk through the classroom to turn your homework in. Wait until the class ends and give it to me before I leave the classroom.

·  There is no partial credit for the numerical mistakes that you may make. Include 4 digits after the period to reduce the rounding error. Each question worth the same with the total homework grade 100 pt.

·  Remember that the 6th edition can be found on the reserve if you did not purchase the book.

·  If the question is asking you to test the hypothesis or answer the question, make sure to show your hypothesis,numeric value of test statistics and pvalue/rejection region, conclusion to get credit. Remember that if the significance level a is not given, it means your p-value is either very large or very small to make a decision. If it comforts you to have the value, you can use a=0.05.

  1. Exercise 9.7
  1. Exercise 9.12 ( Exercise 9.11, 5th edition)
  1. Exercise 9.21 (show both cases: (i) assuming popn. variances are the same (ii) assuming popn. variances are different to get credit for this question)
  1. Exercise 9.29 (show both cases: (i) assuming popn. variances are the same (ii) assuming popn. variances are different to get credit for this question)
  1. Exercise 9.39 (b)
  1. Use the information given for exercise 9.43. Answer part (a) then do not answer part (b) in the question but answer the following as part (b): Use a=0.05 and test to see if there are differences between the true average age at onset of symptoms and the true average age at diagnosis?

7. Exercise 9-47: When you are answering the question to get credit, carefully compute the test statistics, (i) find the P-value and make a decision, (ii) find the rejection region and make a decision. After this write the conclusion.

8. Exercise 9-61