Instructions: Answer each question, and when required explain your answer. Your explanation must be clear and complete. You may refer to your book, your notes and your homework papers.
- Problems 15 and 16 on p. 712.
- Suppose ACT scores in a particular year are approximately normally distributed with mean 20 and standard deviation of 6.
- (a) What z value does 29 represent?
- (b) Use the table on page 709 to determine the proportion of test-takers
that receive a 29 or better on the ACT test.
- (c) What ACT score must you get if 69.15% of test-takers
received a higher score?
- An American Research Group poll of a nationwide random sample of 2,104 likely voters was conducted by telephone March 2-5, 2007. It showed Clinton 42% and McCain 45% (with 10% Undecided). Determine a 95% confidence interval for the 45% McCain figure. Show how you compute your answer.
- A factory produces widgets. The manager believes that only 2% of the widgets produced are defective. How large a sample should the manager take to be 95% sure that the actual rate of defective widgets is between 1% and 3%?
- Problem 27 on p. 741.