PracticeQuestions7 - Practice Questions 7 1 You are...

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Practice Questions 7 1. You are interested in determining the average cost of a 3-minute telephone call to locations within the continental U.S. What sample size must you take to be 96% confident that the results will be within $.75 of the true mean cost per call given that 7.71 σ = ? A) 185 B) 445 C) 406 D) 574 2. Because of the popularity of movies as an entertainment medium for college students, you plan to do a national study of the average cost of a movie ticket. If you assume that σ = $0.50, what sample size would you have to take to be 95% confident that your estimate was within $0.25 of the true mean ticket prices? 3. The Arkansas State Police wish to estimate the average mph being traveled on the Interstate Highways, which cross the state. If the estimate is to be within 8 mpg of the true mean with 98% confidence and the population standard deviation is 22 mph, how large a sample size must be taken? 4. A researcher is interested in determining the proportion of college students who have participated in an internship. How large of a sample should the researcher take in order to estimate the proportion of all college students who have participated in an internship to within 3%? Assume that the researcher wants to have 95% reliability in his results. 5. Assume that the temperature of a blast furnace is normally distributed. A quality control inspector checked the temperature of the furnace at 15 random times over the week, and calculated the 95% confidence interval for the population standard deviation to be 21.4 to 46.0 degrees. What was the sample standard deviation? 6. Match the symbol β with the proper definition. 7. Match the symbol ( 1 α - ) with the proper definition. A) The power of a test. B) The probability of a Type I error. C) The probability of a Type II error. D) The probability of not rejecting the null hypothesis when the hypothesis is true. 8. Match the symbol ( 1 β - ) with the proper definition.
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9. Match the symbol α with the proper definition.
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