III.2. Blood types. Choose a person at random and record his or her blood type. Here are the probabilities for each blood type:
| Blood type: | Type O | Type A | Type B | Type AB |
| Probability: | 0.4 | 0.3 | 0.2 | ? |
(a) What must be the probability that a randomly chosen person has Type AB blood?
(b) To simulate the blood types of randomly chosen people, how would you assign digits to represent the four types?