a. Rewrite the data points (3,1), (6,3), (7,6) and (9,6) with new x-coordinates in mean-deviation form. Let X be the associated design matrix. Why are the columns of X orthogonal? b. Write the normal...

Extracted text: a. Rewrite the data points (3,1), (6,3), (7,6) and (9,6) with new x-coordinates in mean-deviation form. Let X be the associated design matrix. Why are the columns of X orthogonal? b. Write the normal equations for the data in part (a), and solve them to find the least-squares line, y = Bo + B1x, where x =x- 6.25. a. The data in mean-deviation form are (Type ordered pairs. Use a comma to separate answers as needed.) The associated design matrix, X, isO. Therefore, the columns of X are orthogonal because (Simplify your answer. Use ascending order.) b. Write the normal equations for the data from part (a). Select the correct choice below and fi (Simplify your answer.) the entries in one column are all 1 and the entries in the other column sum to 0. O A. the entries in one column are all 1 and the entries in the other column sum to - 1. О в. one column contains all zeros. The least-squares line, y = Po + B,x* , is y = O:x- 6.25).