A person with type B blood can receive a transfusion from someone with type B or type
O blood. What’s the chance of being able to receive a transfusion if you have type B
blood?
P(B or O)
= P(B) + P(O) {because they are disjoint}
= .11 + .45
= .56
b.
Select two people at random. What is the chance they both have type B blood?
P(B
1
and B
2
) = P(B
1
) x P(B
2
)
= (.11)(.11)
= .0121
c.
Select two people at random. What is the chance they both have the same blood type?
P(both O) + P( both A) + P(both B) + P(both AB)
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= P(O)P(O) + P(A)P(A) + P(B)P(B) + P(AB)P(AB)
= (.45)
2
+ (.40)
2
+ (.11)
2
+ (.04)
2
= .3762
d.
Select two people at random. What is the chance that one has type A blood and the other
has type B blood?
P(A
1
and B
2
) + P(B
1
and A
2
) = P(A)P(B) + P(B)P(A) = (.40)(.11) + (.11)(.40) = .088
e.
Select two people at random. What is the chance that exactly one has type A blood?
P(A
1
and not A
2
) + P(not A
1
and A
2
) = P(A)P(not A) + P(not A)P(A)
= (.4)(.6) + (.4)(.6) = .48
Problem 3
The following table lists the joint probabilities associated with having a fast car and the number
of speeding tickets in the last 6 months. Suppose we select a car owner at random from this
sample. Are owning a fast car and getting more than 1 speeding ticket independent?
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 Fall '11
 Johnson
 Statistics, Probability, ABO blood group system, Fast Car

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