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Question

Mathematics Question on Probability

Given two independent events AA and BB such that P(A)=0.3,P(B)=0.6.P(A)=0.3,P(B)=0.6. Find:
(A)P(AandB)P(A\, and\, B)
(B)P(AandnotB)P(A\, and\, not\, B)
(C)P(AorB)P(A or B)
(D)P(neitherAnorB)P(neither\, A\, nor\, B)

Answer

It is given that P(A)=0.3,$$P(B)=0.6
AA and BB are independent events.


(i)P(AandB)=P(A).P(B)P(A\, and\, B)=P(A).P(B)
    P(AB)=0.3×0.6\implies P(A\cap B)=0.3\times 0.6
=0.18=0.18


(ii)PP(AA and not BB)=P(AB)=P(A∩B')
=P(A)P(AB)=P(A)–P(A∩B)
=0.30.18=0.3–0.18
=0.12=0.12


(iii)PP(AA or BB)
=P(A)+P(B)P=P(A)+P(B)–P(AA and BB)
=0.3+0.60.18=0.3+0.6–0.18
=0.90.18=0.9–0.18
=0.72=0.72


(iv)PP(neither AA nor BB)=P(AB)P(A'\cap B')
=1P(AB)=1–P(A∪B)
=10.72=1–0.72
=0.28=0.28