Let X denotes a randomly chosen student's Midterm 1 score and Y denote his/her Midterm 2 score. Suppose X and Y have the following joint pdf, with scores normalized (lying between 0 and 1): f(x)= (2/7)(3x+4y) 0 < x < 1 and 0 < y < 1 You are asked to provide a prediction “?” of the individual's total score X + Y. The error of prediction is the mean squared error E[(X + Y - ?)^2]. What value of ? minimizes the error of this prediction? In other words, what is your best guess of the student’s total (exam 1+ exam 2) score?