Question

A blood bank asserts that a person with type O blood and a negative Rh factor (Rh−) can donate blood to any person with any blood type. Their data show that 49% of people have type O blood and 15% of people have Rh− factor; 45% of people have type O or Rh− factor. Find the probability that a person has both type O blood and the Rh− factor.

Answer 1

The solution to the problem is as follows:

P(O∪Rh−)=0.45

Additive Law of Probability

P(A∪B)=P(A)+P(B)−P(AB)
Therefore,
P(OandRh−)=P(O)+P(Rh−)−P(O∪Rh−)=0.49+0.15−0.45=0.19

I hope my answer has come to your help. Have a nice day ahead and may God bless you always!

Answer 2

Answer:

Probability of a person having both type O blood and the Rh− factor is $19$%

Explanation:

The probability of a person having O blood group is $0.49$

The probability of a person having Rh- factor  is $0.15$

The probability of a person having either O blood group or Rh- Factor is $0.45$

Hence, As per the additive rule of probability

Probability of event A and B together $=$ Probability of A $+$ Probability of A $-$ probability of either A or B

Here event A is occurrence of O blood group

event B is occurrence of Rh- factor

Substituting the given values in above equation, we get -

Probability of a person having both type O blood and the Rh− factor $= 0.49 + 0.15 -0.45\\= 0.19$