The American Red Cross says that about 45% of the U.S. population has Type O blood, 40%

Question:

The American Red Cross says that about 45% of the U.S. population has Type O blood, 40% Type A, 11% Type B, and the rest Type AB.
a) Someone volunteers to give blood. What is the probability that this donor
1. Has Type AB blood?
2. Has Type A or Type B?
3. Is not Type O?
b) Among four potential donors, what is the probability that
1. All are Type O?
2. No one is Type AB?
3. They are not all Type A?
4. At least one person is Type B?