Two car models are tested for a difference in average gas mileage. Ten cars of Model A averaged 32.1 miles per gallon with a standard deviation of 5.2 mpg. Twelve cars of Model B averaged 35.5 mpg with a standard deviation of 4.4 mpg. Calculate a 95% con- fidence interval for the difference between the two cars' mileage. There is no evidence to suggest the variances of the populations are equal. Explain your findings.