SOLUTION: if p(a)=11/20, p(a and b)=77/400, and p(a or b)=283/400, what does p(not b) equal?

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Question 1160381: if p(a)=11/20, p(a and b)=77/400, and p(a or b)=283/400, what does p(not b) equal?
Answer by Boreal(15235) About Me  (Show Source):
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P(A)=11/20
P(A)+P(B)-P(AandB)=P(A or B)
11/20+ P(B)-77/400=283/400
220/400+P(B)=360/400
P(B)=140/400=0.35
P(not B)=0.65