Question

The tree diagram represents an experiment considering of two trials. P(C)=

Answer 1

Answer: P(C) = 0.35

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Work Shown:

P(A) = 0.5

P(C given A) = 0.4 ... follow the uppermost branches.

P(A and C) = P(A)*P(C given A)

P(A and C) = 0.5*0.4

P(A and C) = 0.20

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P(B) = 0.5

P(C given B) = 0.3 ... go from B to C

P(B and C) = P(B)*P(C given B)

P(B and C) = 0.5*0.3

P(B and C) = 0.15

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There are two ways to get to C.

1. Start at A, go to C
2. Start at B, go to C

The first option will have us compute P(A and C). The second option will have us compute P(B and C). Both options are mutually exclusive (you can only pick one path), so that means we can add up the probabilities we found earlier

Therefore we can say....

getting to C = (take path A to C) OR (take path B to C)

P(C) = P(A and C) + P(B and C)

P(C) = 0.20 + 0.15

P(C) = 0.35