Question

A simplified model of the human blood-type system has four blood types: a, b,ab and o. thereare two antigens, anti-a and anti-b. anti-a reacts with blood type a and ab, anti-breactswith b and ab.for a given person, the probability of type a blood is 0.34, type b is 0.12 and type o is 0.5.find theprobability that anti-b will react to this person's blood

Answer 1

First calculate the probability of type AB, which is the remainder after subtracting types A, B and O.

P(AB) = 1-(0.34+0.12+0.5) = 1-0.96 = 0.04

Anti-b will react with types B and AB, so 
P(reaction) = P(B)+P(AB) = 0.12 +  0.04 = 0.16

Answer: For this person, the probability of reaction with anti-b is 0.16