1. Construct a 95% confidence interval for the population standard deviation. Discuss any assumptions you made for the analysis.

Due to environmental concerns and the never-ending volatility of gas prices, drivers are becoming more concerned with their cars’ gasoline consumption. Cameron White, a research analyst at a nonprofit organization, shares these concerns and wonders whether his car’s gas consumption is as efficient as it was when he first bought the new car five years ago. Despite his best intentions, he has been a bit lax in his upkeep of the car and feels that this may adversely influence its performance. At the time he purchased the car, he was told that his car would average 29 miles per gallon (mpg) on highways with a standard deviation of 1 mpg. He records his car’s mpg from the last 20 fill-ups and obtains the following values; these data labeled Gasoline Consumption are also available on the text website.
Data for Case Study 11.1 Gasoline Consumption: Miles per Gallon FILE 26 28 25 29 27 28 30 27 29 28 26 28 29 27 26 27 28 25 28 27 In a report, use the above information to: