申論題

 Jack and John have decided to play a game. One roll of a die is considered as one round of the game. On each round, John agrees to pay Jack $4 if 1 or 2 is rolled, Jack agrees to pay John $2 if 3, 4, 5 or 6 is rolled, and who is paid wins the round. In the end, who earns money wins the game. Now Jack and John roll a die 12 times. Let A denote the number of rounds Jack wins. Find the expected value of A, E[A]= __________.