Chapter 23 HW

Chapter 23 HW - a) Give an expected value and standard...

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Chapter 23 For Problems 1 and 2, consider taking a sample of the given size from a box containing 2,500 tickets, all positive numbers. 1. A sample of 400 tickets has an average of 4.2 and an SD of 0.8. a) What should you estimate the average of the entire box do to be? What is the standard error on your estimate? b) Can you give a meaningful 95% confidence interval for the average value in the box? If so, then estimate it. If not, explain why not. 2. A sample of 80 tickets has an average of 12.6 and an SD of 4. a) What should you estimate the average of the entire box do to be? What is the standard error on your estimate? b) Can you give a meaningful 68% confidence interval for the average value in the box? If so, then estimate it. If not, explain why not. 3. (Hypothetical) Out of a county containing a college, a simple random sample of 1000 people is taken. From the sample, the average level of education (years of school completed, not counting Kindergarten) is 14 years, with an SD of 2 years.
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Unformatted text preview: a) Give an expected value and standard error for the average educational level of people in the county. b) Have 68% of the countys residents completed 14 0.063 years of schooling? Why or why not? 4. (Hypothetical) To determine the number of children that a citys families have, 400 families were randomly surveyed. The average number of children per family was 2.3, with an SD of 0.6. Give a 99.7% confidence interval for the average number of children per family in the town. 5. (Hypothetical) As a way of measuring the quality of English education in one high school, the senior class is required to take the ACT. The English department wants to see an English ACT average of 25. Of the class, 125 tests are checked. The average English ACT score was a 25.4, with an SD of 2.2. Can you say with 99.7% confidence that the English department will get the average it desires? Why or why not?...
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