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Homework Help: Basics and brainlock

  1. Oct 30, 2005 #1
    (100) (.2)x(.8) 100-x
    x
    Trying to solve this using 1, then 2 for x. The same parentheses are around both the 100 and the x.
    Thanks
     
  2. jcsd
  3. Oct 30, 2005 #2

    HallsofIvy

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    Science Advisor

    Do you mean that first term, in which "The same parentheses are around both the 100 and the x" is a fraction: (100/x) or the binomial coefficient?

    Oh, yes, of course, that's a "binomial distribution" calculation:
    [tex]\frac{100!}{x!(100-x)!}.2^x .8^{(100-x)}[/tex]

    With x= 1 that is
    [tex]\frac{100!}{99!}(.2)(.8^{99})[/tex]
    All except the last term are easy. You may want to use a calculator for .899!

    With x= 2 that is
    [tex]\frac{100!}{2(98!)}(.2^2)(.8^{98})[/itex]

    Do the arithmetic! (Cancel a lot in those binomial coefficients first.)
     
    Last edited by a moderator: Oct 30, 2005
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