Consider the model: E1y2 = b0 + b1x1 + b2x2 + b3x3 + e where x1 is a quantitative variable and x2 and x3 are dummy variables describing a qualitative variable at three levels using the coding scheme where x2 = e 1 if level 2 0 otherwise x3 = e 1 if level 3 0 otherwise The resulting least squares prediction equation is yn = 25.94 + 10.6x1 - 1.3x2 + 8.5x3

a. What is the response line (equation) for E1y2 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.