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Unformatted text preview: Chapter 8 Q1 In order to determine the average weight of carry-on luggage by passengers in airplanes, a sample of 36 pieces of carry-on luggage was weighed. The average weight was 20 pounds. Assume that we know the standard deviation of the population to be 8 pounds. Answers a Determine a 97% confidence interval estimate for the mean weight of the carry-on luggage. 17.11 to 22.89 b Determine a 95% confidence interval estimate for the mean weight of the carry-on luggage. 17.39 to 22.61 Q2 The Highway Safety Department wants to study the driving habits of individuals. A sample of 41 cars traveling on the highway revealed an average speed of 60 miles per hour and a standard deviation of 7 miles per hour. The population of car speeds is approximately normally distributed. Answers Determine a 90% confidence interval estimate for the speed of all cars. 58.16 to 61.84 Q3 how large of a sample must be taken in order to be 97% confident Answers that the margin of error will not exceed 40 hours? 265 Q4 Answers Develop a 90% confidence interval for the population proportion. 0.199 to 0.261 Interpret your results. Interpretation of the results: With a 90% level of confidence we can state that the proportion of all college students who read or watch the news every day is between 0.199 and 0.261....
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- Spring '11