SOLUTION: a girl has 10 yellow, 10 red, and 10 green marbles. She picks two marbles out at random and gives them to her sister a.) what is the probability of choosing 2 yellow marbles? b

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Question 352933: a girl has 10 yellow, 10 red, and 10 green marbles. She picks two marbles out at random and gives them to her sister
a.) what is the probability of choosing 2 yellow marbles?
b.) of the marbles left what is the probability of choosing a green marble next?
c.)of the marbles left, what color has the probability of 1/3 of being picked? explain how you determined your answer.

Found 2 solutions by stanbon, robertb:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
a girl has 10 yellow, 10 red, and 10 green marbles. She picks two marbles out at random and gives them to her sister
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a.) what is the probability of choosing 2 yellow marbles?
P(2 yellow) = 10C2/30C2 = 0.1034
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b.) of the marbles left what is the probability of choosing a green marble next?
P(green after 2 yellow) = 10/28
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c.)of the marbles left, what color has the probability of 1/3 of being picked? explain how you determined your answer.
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27 marbles are left
There are 9 green left.
P(green) = 9/27 = 1/3
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Cheers,
Stan H.

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
The number of ways of getting 2 marbles out of 30 is C(30, 2).
The number of ways of getting 2 yellow marbles out of 10 yellow marbles is
C(10, 2).
a.) Thus The probability of choosing 2 yellow marbles is
C%2810%2C+2%29%2FC%2830%2C+2%29+=+45%2F435+=+3%2F29
b.) Of the marbles left there are 8 yellow, 10 red , 10 green. Thus the probability of choosing 1 green marble next is 10%2F28+=+5%2F14.
c.) After picking a green marble, there are 8 yellow, 10 red, 9 green marbles left. So there are 27 marbles remaining. Of these the green colored marble has probability 9%2F27+=+1%2F3 of being picked.