SOLUTION: Bag A contains 15 marbles of which are 8 red and the rest are black. Bag B contains 14 marbles of which 4 are red and 3 are blue and the rest are black. A ball is drawn at random f

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Question 1033649: Bag A contains 15 marbles of which are 8 red and the rest are black. Bag B contains 14 marbles of which 4 are red and 3 are blue and the rest are black. A ball is drawn at random first from bag A, and second from bag B. If we make the random variable be black marbles (B).
A)Create a tree diagram...

Hi there I am just unsure how to start the tree diagram. I have two problems similar to this one but I need help on how to start it.

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
i believe your tree diagram will look something like this.
$$$
you first draw from bag A.
the probability of getting a black marble is 7/15.
you then draw from bag B.
the probability of getting a black marble from bag B is 7/14.
the probability of first drawing a black marble from bag A and then drawing a black marble from bag B is therefore 7/15 * 7/14 = 49/210.
this can be simplified to 7/30.
here's a tutorial on how to draw tree diagrams.
https://www.mathsisfun.com/data/probability-tree-diagrams.html
there are others.
just do a search for "how to draw a tree diagram" or something like that.
if you add up all the probabilities, they should be equal to 1.