Question

Human blood is classified by the presence or absence of three main antigens (A, B, and Rh). When a blood specimen is typed, the presence of the A and/or B antigen is indicated by listing the letter A and/or the letter B. If neither the A nor the B antigen is present, the letter O is used.

The following table gives the percent of a country's population having each of the eight possible blood types in the sample space. Note that the presence or absence of the Rh antigen is indicated by the symbols + or −, respectively.

Blood Types	A+	A−	B+	B−	AB+	AB−	O+	O−
Percent	35.7	6.3	9.5	2.5	3.4	0.8	37.4	4.4

(a) What is the probability that a person selected at random from the population has a blood type that is type A given that the person is Rh⁻? (Round your answer to two decimal places.)


(b) What is the probability that a person selected at random from the population has a blood type that is Rh⁺ given that the person is type B? (Round your answer to two decimal places.)

Answer 1

a) P(Type A | Person in Rh-)

= 6.3 / (6.3 + 2.5 + 0.8 + 4.4)

= 0.45

b) P(Rh+ | Type B)

= 9.5/(9.5 + 2.5)

= 0.79