SOLUTION: Two marbles are selected at randomly from a box containing 5red,7white and 8blue marbles one after the other without replacement. Draw a probability tree diagram and find the proba

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Question 1156069: Two marbles are selected at randomly from a box containing 5red,7white and 8blue marbles one after the other without replacement. Draw a probability tree diagram and find the probability that:
1.both are red
2.one is white and the other is blue
3.both are the same color

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
both are red, the red tree with (5/20) for the first and (4/19) for the second or 1/18 altogether
one is white and the other is blue.
WB is 7/20*8/19
BW is 8/20*7/19
that total is 112/380 with probability 0.2947
same color is RR or 1/18 or 0.0556
WW which is (7/20),(6/19)=42/380 or 21/190 or 0.1105
BB which is (8/20)(7/19)=56/380=14/95 or 0.1474