Question 4 [3+3: 3 points]: [Hon] Weisberg, EDGE] We are interested in the linear model Y29+1$1+232+ {a} Suppose we t the model above to data for which $1 = 2.21:2 with no error (that is, all residuals = [l ). For example, X1 could be a weight in pounds, and X2 the weight of the same object in kg. Describe the appearance of the addedvariable plot for $2 after 331 had been added to the above model. Explain why. Assume that Y has a correlation with the predictors that is neither 0 nor 1 . Hint: Think about what goes on the .raads and the yaxis of the added variable plot. You should notice something interesting about one of those residual vectors. {b} Again referring to the model above, this time suppose that Y and X1 are perfectly correlated, so Y 2 3X1, without any error. Describe the appearance of the addedvariable plot for 1:2 after r1 had been added to the model. Explain. Assume this time that the correlation between the predictors is between D and 1