In order to estimate the difference between the average miles per gallon of two different models of automobiles,' samples are taken and the fallowing information is collected. model a model b sample size 60 55 sample mean 28 25 sample variance 1:6 9 (a) at 95% confidence develop an interval estimate for the difference between the average miles per gallon for the two models. . . (b) is there conclusive evidence to indicate that one model gets a higher mpg than the oth er? why or not? explain.