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Solve for n help

  1. Jan 15, 2006 #1


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    There are no answers given for these questions because they are based on my entire book.

    Can anyone verify my answer for this question.
    Solve for n

    1. P(n,3)=6P(n-1,3)

    When i solve for n i get 3.6.

    2.Determine the number of divisors for the number 3780, using the fact that a divisor of a number is the multiplication of one or more of the factors of the number.

    I know this questions is really easy. I know i can easily just use my calculator and go through every single number but is there a shorter way of doing this.

    3. A game is played by drawing cards from a deck that has all face cards including aces removed. The player draws a card and is paid the face value of the card in dollars. Each play costs $5.00. how much would you expect to win or lose if you played the game 20 times?

    I have no idea how to do this one.

    4. A manufacting company precut tubing for lawn chairs. Management has decided that they can accept 15% of their production outside specified tolerances. The floor manager samples 10 parts per hour from the production and stops the line if 2 parts or more from the sample are outside the tolerance.
    a)If the actual defect rate is 16%, what is the probability that the line would be shutdown
    b)For the same defect rate, what is the probability that the line would be shut down if the sample was increased to 20 parts but production was still stopped when 2 defects were found.

    For a) i did
    1-[P(X=0) + P(X=1)]
    I dont have time to show my work but i used the binomial experiment formula and i get 0.492 as an answer i think thats a bit high.
    But i dont even know what that 15% is for.

    So can anyone please help with these questions.
  2. jcsd
  3. Jan 15, 2006 #2
    what do you mean by P
    Do you mena permutation as in [tex] P(n,r) = \frac{n!}{(n-r)!} [/tex] in which case you are correct.

    2) well i cant type it all here but i do it like this
    3780 = 2 x 1890
    1890 = 2 x 945
    945 = 5 x 189
    189 = 3 x 63
    63 = 3 x 21
    21 = 3 x 7
    7 = 7 x 1
    hope that helps
  4. Jan 16, 2006 #3


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    For P i do mean Permutation. But what about my other questions
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