Question 948396: If P(A) = 0.5, P(AandB) = 0.3, and P(AorB) = 0.6, find P(B).
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A an B are independent events. P(A) = 0.3, and P(A or B) = 0.8. Find P(B). The more I see, the more I get confused.
Thanks in advance.
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website! If P(A) = 0.5, P(AandB) = 0.3, and P(AorB) = 0.6, find P(B).
P(A or B) = P(A) + P(B) - P(A and B)
0.6 = 0.5 + P(B) - 0.3
0.6 = 0.2 + P(B)
0.6 - 0.2 = P(B)
0.4 = P(B)
P(B) = 0.4
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A an B are independent events. P(A) = 0.3, and P(A or B) = 0.8. Find P(B).
x = P(B)
"A an B are independent events" so P(A and B) = P(A)*P(B)
P(A or B) = P(A) + P(B) - P(A and B)
P(A or B) = P(A) + P(B) - P(A)*P(B)
0.8 = 0.3 + x - 0.3*x
0.8 = 0.3 + 0.7*x
0.8 - 0.3 = 0.7*x
0.5 = 0.7*x
0.5/0.7 = x
5/7 = x
x = 5/7
x = 0.71429 (this is approximate)
P(B) = 5/7 which is approximately 0.71429
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