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Suppose an urn contains 8 red,5 white and 7 blue marbles.If 3 marbles are drawn at random from the urn with replacement,what is the probability that three marbles are the same color?Give answer in a reduced fraction.
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Melina

could be RRR , WWW, or BBB
prob = (8/20)(7/19)(6/18) + (5/20)(4/19)(3/(18) + (7/20)(6/19)(5/18)
= 336/6840 + 60/6840 + 210/6840
= 606/6840
= 101/1140posted by Reiny
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