Let's try to calculate the basic probability. Suppose that we are using a deck of cards. 1. Excluding Joker, how many cards do we have? 2. Then, how many cards are red? 3. Therefore, the probability of getting a red card is over . 4. How many cards are 'King'? 5. Therefore, the probability of getting a King is over . 6. The joint probability of a red card and a king is over . 7. The probability of the card be red or King is over