Red Cross Rh. Exercises 36 and 38 discussed the challenges faced by the Red Cross in finding enough blood of various types. But blood typing also depends on the Rh factor, which can be negative or positive. Here is a table of the estimated proportions worldwide for blood types categorized on both type and Rh factor:

Blood Type O A B AB Rh

 36.44% 28.27% 20.59% 5.06%

 4.33% 3.52% 1.39% 0.45%

For a randomly selected human, what is the probability that he …

a) Is Rh negative given that he is type O?

b) Is type O given that he is Rh negative?

c) A person with Type A- blood can accept donated blood only of types A- and O-. What is the probability that a randomly selected donor can donate to a recipient given that the recipient’s blood type is A-?