Question

Suppose that there is a black urn containing nine black balls and three yellow balls and there is a yellow urn containing six black balls and six yellow balls. An experiment consists of selecting at random a ball from the black urn and then (without replacing the first ball) selecting at random a ball from the urn having the color of the first ball.

1. Construct a tree diagram showing the probabilities associated with this problem. Write a probability on each branch (6 branches). Multiply the the probabilities along each path and write that number at the end of the path (4 answers).
2. Find the probability that the second ball is yellow.

Answer 1

See Annex ( Tree diagram )

Explanation:

1) Attached

2) Probability of the second ball is yellow is

P(2nd ball is yellow ) = Probability 2nd ball s yellow (if the first one was black) + Probability 2nd ball s yellow (if the first one was Yellow)

P(2nd ball is yellow ) = 0,204 + 0,045

P(2nd ball is yellow ) = 0,249