Math Finite

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A box contains 15 pens of which 4 are defective. A random sample of 3 pens is taken without replacement and without regard to order. What is the probability of selecting at least one defective pen?

  • Math Finite -

    What you want in the probability of selecting 1, 2 or 3 defective pens.

    P of 3 = 4/15 * 3/14 * 2/13

    P of 2 = 4/15 * 3/14 * 11/13

    P of 1 = 4/15 * 11/14 * 10/13

    The answer is the sum of those three products.

  • Math Finite -

    0.2442

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