SOLUTION: A student's pencil case contains six red pencils and eight black pencils. If seven pencils are picked at random, what is the probability that exactly three of them are black?
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Question 1106137: A student's pencil case contains six red pencils and eight black pencils. If seven pencils are picked at random, what is the probability that exactly three of them are black? Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! Total number of ways to choose 7 from 14 is 14C7 (denominator)
numerator are ways to choose 3 black pencils, 8C3, multiplied by ways to choose 4 red pencils, 6C4.
That is 56*15=840 divided by 3432
probability is 0.245
