The distribution of blood types in the United States is as follows, where positive and negative refer to the Rhesus (Rh) factor:

O-positive: 37 %

O-negative: 7 %

A-positive: 35 %

A-negative: 6 %

B-positive: 9 %

B-negative: 2 %

AB-positive: 3 %

AB-negative: 1 %

If you draw blood samples and determine Rh factor using five randomly selected people from this population,

a) What is the random variable?

b) What is the probability that two of the blood samples will be Rh negative?

c) What is the probability that two of the blood samples will be Rh positive?