Question

Every Persons blood belongs to one of four blood groups. The percentage of U.S. blood donors to the Red Cross is given:

Type A=37% B=12.5% AB=3.5% O=47%

a)What is the Probability that the blood of any two unrelated people in a Red Cross blood drive belong to the same group?

Is this correct?
P(Ba)=.37 P(Bb)=.125 P(Bab)=.035 P(Bo)=.47

P(Samegroup)=P(Ba)^2+P(Bb)^2+P(Bab)^2+P(Bo)^2= 0.37465 ?

b)What is the probability that the blood of any four unrelated people in an american red cross blood drive belong to each of the four groups?

Answer 1

a) correct
b) four unrelated people standing in a row. Probability that they are in this exact order: A, B, AB, O is .37*.125*.035*.47 = .0007608
Now then, the number of ways these four people can be re-arranged is 4*3*2*1 = 24.
So, Probability is 24*.0007608 = .01826