12.84 Consider the model: y = BO + $1x1 + /2x2 + $3x3+ & where x1 is a quantitative variable and x2 and x3 are dummy variables describing a qualitative variable at three levels using the coding scheme 1 if level 2 1 if level 3 x2 = 1 0 otherwise x3 = 10 otherwise The resulting least squares prediction equation is y = 44.8 + 2.2x1 + 9.4x2 + 15.6x3 a. What is the response line (equation) for E(y) when x2 = x3 = 0? When x2 = 1 and x3 = 0? When x2 = 0 and x3 = 1? b. What is the least squares prediction equation associated with level 1? Level 2? Level 3? Plot these on the same graph