Question 306608: Suppose there are 10 balls in an urn, 4 blue,4 red , 2 green. The balls are also numbered 1 to 10. How many ways are there to select an ordered sample of 4 balls without replacement such that there are 2 blue balls and 2 red balls in the sample?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Suppose there are 10 balls in an urn, 4 blue,4 red , 2 green. The balls are also numbered 1 to 10. How many ways are there to select an ordered sample of 4 balls without replacement such that there are 2 blue balls and 2 red balls in the sample?
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# of ways to select 2 blue balls: 4C2 = 6
# of ways to select 2 red balls:: 4C2 = 6
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# of ways to select 4 random balls from 10 : 10C4 = 210
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P(2 blue and 2 red) = (6*6)/210 = 36/210 = 0.17
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Cheers,
Stan H.
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