3. A response variable is related to a predictor variable through the quadratic regression model Y|X(x) = 8.5 3.2x + 0.7x2. (a) Give the rate

3. A response variable is related to a predictor variable through the quadratic regression model μY|X(x) = −8.5− 3.2x + 0.7x2.

(a) Give the rate of change of the regression function at x = 0, 2, and 3.

(b) Express the model in terms of the centered variables as μY|X(x) = β0 + β1(x − μX) + β2(x −

μX)2. If μX = 2, give the values of β0, β1, and β2.

(Hint. Match the coefficients of the different powers of x.)