United Oil Company is attempting to develop a reasonably priced unleaded gasoline that will deliver higher gasoline mileages than can be achieved by its current unleaded gasolines. As part of its development process, United Oil wishes to study the effect of two independent variables?x₁, amount of gasoline additive RST (0, 1, or 2 units), andx₂, amount of gasoline additive XST (0, 1, 2, or 3 units), on gasoline mileage,y. Mileage tests are carried out using equipment that simulates driving under prescribed conditions. The combinations ofx₁andx₂used in the experiment, along with the corresponding values ofy, are given below.

8 2 32.68 8 2 33.84 1 2 34.64 1 2 35.46 1 2 35.96 2 2 33.76 2 2 34.57 2 2 34.79 1 3 33.28 2 3 32.76 2 3 33.41 Using the model,y = 63 + 61x1 + 62x12 + 83x; + 64,sz + a, calculate the point estimate. (Moreover, consider the mean mileage obtained by all gallons of the gasoline when it is made with one unit of RST and two units of XST (a combination that the data on the page margin indicates would maximize mean mileage). Do not round intermediate calculations. Round your answer to 4 decimal places.) 9 Answer is complete but not entirely correct. Point estimate | 35.1307 6 l United Oil Company is attempting to develop a reasonably priced unleaded gasoline that will deliver higher gasoline mileages than can be achieved by its current unleaded gasolines. As part of its development process, United Oil wishes to study the effect oftwo independent variablesX1, amount of gasoline additive RST (0, 'l, or 2 units}, and )9, amount of gasoline additive XST (O, 1, 2, or 3 units), on gasoline mileage, y. Mileage tests are carried out using equipment that simulates driving under prescribed conditions. The combinations of x1 and X2 used in the experiment, along with the corresponding values ofy, are given below. RST XST Gas Units Units Mileage (X1) (X2) ()5 mpg) B 8 27.43 B 8 28. B7 6 8 28.46 1 8 29. 38 1 8 38. BB 2 8 28. 14 2 B 29. 58 B 1 32.43 8 1 33 . 95 1 1 33. 96 1 1 34. 77