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13#
发表于 2013-4-28 07:11
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ana_georgiana90 wrote:
why is it not correct to calculate p(A andB)= 0.21 and then p(non(Aand B)= 1 - 0.21 = 0.79?
In this case you are looking for P(not(AorB)) not p(not(AB)). Therefore, once you get P(AandB) you need to use addition rule P(A or B)= P(A) + P(B)-P(AandB)= 0.60+0.35-0.21= 0.74. P(AorB)= 0.74 so P(not(AorB) = .026. |
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