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 their probabitlity that this donor:

1. has Type AB blood?

2. has Type A or Type B blood?

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?