Question

Here is the probability model for the blood type of a randomly chosen person in the United States.

Blood Type	O	A	B	AB
Probability	0.31	0.34	0.12	?

(a) What is the probability that a randomly chosen American has type AB blood? Please use 2 decimal places.


(b) Maria has type B blood. She can safely receive blood transfusions from people with blood types O and B. What is the probability that a randomly chosen American can donate blood to Maria? Please use 2 decimal places.


(c) What is the probability that a randomly chosen American does not have type O blood? Please use 2 decimal places.

Answer 1

Given that

Blood Type	O	A	B	AB
Probability	0.31	0.34	0.12	?

Let probability of AB is x

Probability = 1

p = 0.31 + 0.34 + 0.12 +x = 1

p= 0.77+x = 1

x = 1-0.77 = 0.23

x =0.23

a) probability that a randomly chosen American has type AB blood is 0.23

b) Maria has type B blood. She can safely receive blood transfusions from people with blood types O and B.

probability that a randomly chosen American can donate blood to Maria:

P[randomly chosen American can donate blood to Maria:] = P[ O blood types] + P[B blood types]

P[randomly chosen American can donate blood to Maria:] = 0.31 + 0.12 = 0.43

P[randomly chosen American can donate blood to Maria:] = 0.43

c)probability that a randomly chosen American does not have type O blood:

P[ randomly chosen American does not have type O blood] = 1- P[ O blood type]

P[ randomly chosen American does not have type O blood] = 1-0.31 = 0.69

P[ randomly chosen American does not have type O blood] = 0.69