SOLUTION: P (A or B)= 1/4, P (A)= 1/6, and P (A and B)= 1/7 find P (B)

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Question 1022580: P (A or B)= 1/4, P (A)= 1/6, and P (A and B)= 1/7 find P (B)
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
Normally
P(A or B) = P(A) + P(B) - P(A and B)
Let's plug in and find P(B)
1/4 = 1/6 + P(B) - 1/7
so that
P(B) = 1/4 - 1/6 + 1/7
P(B) = 21/84 - 14/84 + 12/84
P(B) = 19/84