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Math Help - Can some help me on this Log. word problem?

  1. #1
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    Can some help me on this Log. word problem?

    Determine the probablilty that x=5 people will enter in the next minute.

    The formula given is p(x) 4^x e^-4/ x!

    where x!= x* (x-1)*(x-2).......3*2*1




    Thanks

    Jason
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by Darkhrse99 View Post
    Determine the probablilty that x=5 people will enter in the next minute.

    The formula given is p(x) 4^x e^-4/ x!

    where x!= x* (x-1)*(x-2).......3*2*1




    Thanks

    Jason
    And have you tried putting x=5 in:

     <br />
p(x) = \frac{4^x e^{-4}}{ x!}<br />

    RonL
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  3. #3
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    If I put X=5 i for x I'd get

    <br />
p(x)=\frac{4^5 e^{-4}}{ x!}<br />
    How would I solve it?
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Darkhrse99 View Post
    If I put X=5 i for x I'd get

    <br />
p(x)=\frac{4^5 e^{-4}}{ x!}<br />
    How would I solve it?
    and what about the x in the denominator?
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  5. #5
    Grand Panjandrum
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    Quote Originally Posted by Darkhrse99 View Post
    If I put X=5 i for x I'd get

    <br />
p(x)=\frac{4^5 e^{-4}}{ x!}<br />
    How would I solve it?
    <br />
p(x)=\frac{4^5 e^{-4}}{ 5!}=\frac{4^5 e^{-4}}{ 5\times4\times 3\times 2 \times 1}<br />

    Now do you have a calculator?

    RonL
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  6. #6
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     p(x)=\frac{1024 }{120} = .15
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  7. #7
    Bar0n janvdl's Avatar
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    Quote Originally Posted by Darkhrse99 View Post
     p(x)=\frac{1024 }{120} = .15
    Yes i got 0,15 too.

    0,1562934519 to be precise.

    So that should be a chance of 15,629 % approx.


    EDIT: Check your calculations.  1024 \div 120 is definitely not smaller than 1... And it's equal to 8,533 not 0,15 or even 15...
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  8. #8
    Bar0n janvdl's Avatar
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    Quote Originally Posted by Darkhrse99 View Post
    Sorry about that 1024 / 120 is 8.533.
    But 4^5 e^{-4} = 18,75521422
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  9. #9
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    p(x)=\frac{1024 e^{-4}}{ 120}<br />
=.1540
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  10. #10
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    p(x)=\frac{18.4839}{ 120}<br />
=.1540 chance of someone waling through the door.
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  11. #11
    Bar0n janvdl's Avatar
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    Quote Originally Posted by Darkhrse99 View Post
    p(x)=\frac{18.4839}{ 120}<br />
=.1540 chance of someone waling through the door.
    Yes i guess our calculators work differently. That's close enough.
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  12. #12
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    Thanks for the help. I would have never guessed that x! means 5*4*3*2.....
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  13. #13
    Bar0n janvdl's Avatar
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    Quote Originally Posted by Darkhrse99 View Post
    Thanks for the help. I would have never guessed that x! means 5*4*3*2.....
    It's the factorial of 5.

    1! = 1

    2! = 1 x 2

    3! = 1 x 2 x 3

    4! = 1 x 2 x 3 x 4

    You get the idea.
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  14. #14
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    I understand it now, but I was never aware of it before. I was never taught that in class, but I have it for homework. It's a little frustrating.
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  15. #15
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    probability

    the formula for p(x) you posted must be related to some defined conditions. a p of .15 is high. it could be true in a school office given school population and average daily traffic but the p of this event for visitors coming to my house in the next minute is close to zero. what were your conditions?
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