Suppose we have a linear regression model Yi = 0 + 1Xi + ui (1) a. Show that ESS = 1 2 Pn i=1(Xi X)2. b. Suppose the sample correlation coefficient between {Xi}and {Yi}is r. Show that the regression R2 = r2. (Tip: use the result from Question (a)) c. Suppose we reverse X and Y and have the following linear regression Xi = 0 + 1Yi + i (2) Show that if regression (1)s R2 = 1, then 1 = 1/ 1. ( Tip: use the result from Question (b))