Consider the multiple regression output shown: The regression equation is Y = 44.1 - 6.67X1 + 1.58X2 + 1.62X3 + 0.418X4. Predictor Coef SE CoefT P Constant 44.11 19.10 2.310.060 X1 -6.672 1.036-6.440.001 X2 1.581 1.106 1.430.202 X3 1.6164 0.5712 2.830.030 X4 0.4184 0.1390 3.010.024 S = 2.04939R - Sq = 99.8%R - Sq (adj) = 99.6% Analysis of Variance Source DFSS F P Regression 410886.02721.5650.660.000 Residual Error 6 25.2 4.2 Total 1010911.2 Select all the variables which are significant at the 5% level. O X1 O X2 O X3 O X4