c) A regression analysis was performed based on model E(Y) = Bo + B1X1 + BzX2 + B3X3 and the following output was obtained. Analysis of Variance Sum of Mean Source DF Squares SquareF ValuePr > F Model 3 2176606 725535 35.34K.0001 Error 48 985530 20532 Corrected Total 51 3162136 Parameter Standard VariableDF Estimate Error Intercept 1 4149.88721 195.56541 X1 1 0.000787080.00036455 X2 -13.16602 23.09173 X3 623.55448 62.64095 Determine whether any of the predictor variables can be dropped from the model. Use a = 0.05 (4 marks) d) Percentage of labor hours and the appearance of the product in flyer are believed to have interaction effect on sales of yogurt drinks. Thus, a new model E(Y) = Bo + BIX, + B2X2 + B3X3 + B4X2X3 is fitted to the data and the following result was obtained: Analysis of Variance Sum of Mean Source DF Squares SquareF ValuePr > F Model 4 2209382 552346 27.25 .0001 Error 47 952753 20271 Corrected Total 51 3162136 Do you agree that interaction effect is significant in determining the sales of the yogurt drinks? Justify your answer at 5% significance level. (4 marks)