Consider the "centered" (with respect to the independent variable) model in scalar form: Y, = M+ B,(X, - X)+&, i=1,...,n &, ~ NID(0,62) a. Obtain the normal equations and the least squares estimated for the parameters u and B1. A n b. Derive COV u, B. Hint: COV [a,y,, [b, Y, = EEab, cov ( Y,, Y,) i=1 i=1 j=1