2. A carbon dioxide (CO2) flooding technique is used to extract crude oil. The CO floods oil pockets and displaces the crude oil. In an experiment, flow tubes are dipped into sample oil pockets containing a know amount of oil. Using three different values of flow pressure and three different values of dipping angles, the oil pockets are flooded with CO2, and the percentage of oil displaced recorded. Pressure (lb/in) 1000 Dipping Angle Oil Recovery (%) 0 60.58 1000 15 72.72 1000 30 79.99 1500 0 66.83 1500 15 80.78 1500 30 89.78 2000 0 69.18 2000 15 80.31 2000 30 91.99 a) Please determine whether there is a significant linear correlation between the oil recovery and the two explanatory variables at the 0.05 level of significance using t test approach. (/4) b) At the 0.05 level of significance, use F-test to determine whether each explanatory variable make a significant contribution to the linear regression model. On the basis of these results, indicate the regression model that should be used in this problem. (/6)