United Oil is attempting to develop a middle-grade gasoline that will deliver high gasoline mileages. As part of its development process, United Oil will study the effect of three middle-grade gasoline types (A, B, and C) and the amounts 0, 1, 2, and 3 units of additive VST. Mileage tests are run, with the results shown on the page margin. (1) Develop an appropriate model describing these data. (2) Use the model to find a point estimate of and a 95 percent confidence interval for mean mileage when the middle-grade gasoline is made with gasoline type B and one unit of additive VST.

Transcribed Image Text:

Gas Gas VST Mileage Type Units (mpg) 27.9 28.4 A 27.5 33.1 34.6 32.9 A 32.1 35.7 34.4 35.1 34.0 33.4 34.6 A 2 33.4 32.1 33.3 2 33.1 2 32.1 29.5 B 3 30.6 3 28.5 29.9