Question

Find the missing probability.

Answer 1

Answer: P(B) = 7/20

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Work Shown:

Given info

P(A) = 7/20

P(A∩B)=49/400

P(B) = unknown

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P(A∩B) = P(A)*P(B), assuming A and B are independent events

49/400 = (7/20)*P(B)

(7/20)*P(B) = 49/400

P(B) = (20/7)(49/400)

P(B) = (20*49)/(7*400)

P(B) = (20*7*7)/(7*20*20)

P(B) = 7/20

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Note how

P(A∩B) = P(A)*P(B)

P(A∩B) = (7/20)*(7/20)

P(A∩B) = (7*7)/(20*20)

P(A∩B) = 49/400

which helps to confirm the answer.