Homework Sourse3 A and B are independent events pA 8 pB 4 a pAB b pA u B
3. A and B are independent events; p(A) = .8; p(B) = .4
a) p(AB)
b) p(A u B) =
c) p(A / B) =
d) p(BC / A) =
Solution
a) p(AB) = P(A)*P(B) = 0.8*0.4 = 0.32
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b) p(A u B) =P(A)+P(B)- P(A and B)
=0.8+0.4-0.32
=0.88
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c) p(A / B) = P(A and B)/P(B)
=0.32/0.4
=0.8
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d) p(BC / A) = P(B\' and A)/P(A)
=(P(A)-P(A and B)) / P(A)
=(0.8-0.32)/0.8
=0.6
