4.10 Two tire-quality experts examine stacks of tires and assign a quality rating to each tire on a 3-point scale. Let X denote the rating given by expert A and Y denote the rating given by B. The following table gives the joint distribution for X and Y. f (x, y) 3 0.10 0.05 0.02 0.10 ( 0.35 0.05 0.03 0.10 0.20 Find ex and by