Car manufacturers are concerned about meeting new government regulations on fuel efficiency. Audi knows that their average mile per gallon (mpg 16-38) of their entire line of automobiles in 2000 was 27.93 and their current line of automobiles (N=24) is 30.67 but they do not know the variance of the population (year 2000). They would like to use the line in 2000 as the standard to compare the current line to see if their mpg is improving and they are making progress to meeting government regulations. What are the independent and dependent variables and thier scaling? What statistical test should be used and what are the assumptions? What is the df?