An environmental agency is interested in the fuel efficiency of cars in a local city. The research department took a random sample of 40 cars and determined the mean city miles per gallon (mpg) was...

An environmental agency is interested in the fuel efficiency of cars in a local city. The research department took a random sample of 40 cars and determined the mean city miles per gallon (mpg) was 21.43 mpg with a standard deviation of 5.72 mpg. Construct a 90% confidence interval for the mean city miles per gallon of all vehicles.