Bag a contains 3 red balls and 1 blue ball. A bag b contains 1 red ball and 1 blue ball. A ball is randomly picked from each bag. The ball from bag a is the placed into bag b and the ball from bag b is placed into bag a. What is the expected number (or mean) of red balls in the bag a?.

Case # 51173878 weighs 814 pounds; case # 51173981 weighs 803 pounds; case # 51174058 weighs 817 pounds; case 51174178 weighs 815 pounds; case # 51174248 weighs 817 pounds; case # 51174495 weighs 781 pounds; case # 51174577 weighs 828 pounds. what are the case #'s of the two cases that weigh the same amount?