Consider the following data with the dependent variable y, independent variable x, and the dummy variable d. 100 0 9.3 100 6.5 50 0 4.2 75 7.4 65 0 6.0 90 1.6 85 9.6 65 6.5 50 6.0 75 9.9 75 8.6 65 4.9 95 7.2 95 9.9 90 7.8 80 7.2 75 7.0 95 8.7 100 9.9 90 19.3 70 9.1 100 8.9 40 5.4 90 8.8 75 8.8 40 5.0 45 6.555 5.2 100 10.0 190 8.4 80 5.4 80 6.7 90 8.5 8.9 6.3 7.5 6.8 5.7 4.5 a. Check if the overall regression relationship exists for the above data. If yes, test the relationship between each independent variable and the dependent variable at the 0.05 level of significance, and interpret the relationship between each of the independent variables and the dependent variable. b. How much of the variation in the sample values of delay does this estimated regression equation explain