SOLUTION: A box contain 6 white, 5 red and 4 black pencils. Fin the probability of getting at least two red pencils if four pencils are drawn

Question 1026451: A box contain 6 white, 5 red and 4 black pencils. Fin the probability of getting at least two red pencils if four pencils are drawn

Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
Probability(X > = 2) = 1 - (Pr(X=0) + Pr(X=1))
:
This says the Probability(Pr) that at least 2 pencils picked without replacement is equal to 1 minus the probability of no red pencils picked plus the probability that 1 red pencil is picked
:
Pr(X=0) = (10/15)*(9/14)*(8/13)*(7/12) = 0.153846154
Pr(X=1) = (5/15)*(10/14)*(9/13)*(8/12) = 0.10989011
:
Pr(X > = 2) = 1 - (0.153846154 + 0.10989011)
Pr(X > = 2) = 1 - 0.263736264 = 0.736263736
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Pr(X > = 2) is approx 0.74
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