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Almost done but got stuck

  1. Sep 28, 2009 #1
    Hi, I'm almost at the end of a question but i seem to be stuck. I have the answer though.. so im up to here so can someone please help me complete this:

    [tex] (\frac{n + \frac{1}{c}}{\frac{s}{n} }) [\mu^2 - 2\mu(\frac{n \overline{y}}{n+\frac{1}{c}})] [/tex]
    then i completed the square:
    [tex](\frac{n + \frac{1}{c}}{\frac{s}{n} }) [(\mu - \frac{n\overline{y}}{n + \frac{1}{c}})^2 - (\frac{n\overline{y}}{n + \frac{1}{c}})^2][/tex]

    then i expanded it:
    [tex] (\frac{n + \frac{1}{c}}{\frac{s}{n} })(\mu - \frac{n\overline{y}}{n + \frac{1}{c}})^2 - (\frac{n + \frac{1}{c}}{\frac{s}{n} })(\frac{n\overline{y}}{n + \frac{1}{c}})^2 [/tex]

    then i guess:
    [tex] (\frac{n + \frac{1}{c}}{\frac{s}{n} })(\mu - \frac{n\overline{y}}{n + \frac{1}{c}})^2 - [/tex][tex] (\frac{n + \frac{1}{c}}{\frac{s}{n} })(\frac{1}{(\frac{n\overline{y}}{n + \frac{1}{c}})^2 })[/tex]

    and then i tried really hard to simplify it but i cant get the answer...

    then answer is:
    [tex]\frac{n + \frac{1}{c}}{\frac{s}{n} + \frac{\overline{y}(\frac{1}{c})}{(n + \frac{1}{c})}}[\mu - (\frac{n\overline{y}}{n + \frac{1}{c}})]^2[/tex]

    am i doing it right so far? and if so, then can you please help me figure out the next line, coz i tried and i cant somehow get that answer..:(.. thank you..?
     
  2. jcsd
  3. Sep 28, 2009 #2

    mathman

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    What is the statement of the original problem????
     
  4. Sep 28, 2009 #3

    arildno

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    Do you have some equations relating some of the variables together, so that they are not fully independent of each other?

    Otherwise, I don't think you will make it.

    Please post the precise question, so that we can look at it from there!
     
  5. Sep 28, 2009 #4
    yeahh i think that i must have done something wrong along the way, coz i don't think that i could make it too..

    well the actual problem was to show:
    [tex] p(t|y) \propto (1 + \frac{n + 1/c}{\frac{s}{n} + \frac{\overline{y^2}(1/c)}{n + 1/c}})(\mu - \frac{n\overline{y}}{n + 1/c})^2 [/tex]

    but yeahhh what i showed you guys is where im up to which is sorta 3/4 of the way done i think. but yeahh i started again after reading all your posts, so do you think that it's possible to get from
    [tex] (\frac{n + 1/c}{\frac{s}{n}})[\mu - \frac{n\overline{y}}{n + 1/c}]^2 [/tex]

    and make it equal to
    [tex]
    \frac{n + \frac{1}{c}}{\frac{s}{n} + \frac{\overline{y}(\frac{1}{c})}{(n + \frac{1}{c})}}[\mu - (\frac{n\overline{y}}{n + \frac{1}{c}})]^2 [/tex]

    like i tried
    [tex] \frac{n + \frac{1}{c}}{\frac{s}{n} + \frac{\overline{y}(\frac{1}{c})}{(n + \frac{1}{c})}}[\mu - (\frac{n\overline{y}}{n + \frac{1}{c}})][\mu - (\frac{n\overline{y}}{n + \frac{1}{c}})][/tex]

    and expanding out only the first two brackets and that didn't work out too..
    so did i do something wrong again and it's not possible to get to the right answer with what im up to so far? and should i start again?
     
  6. Sep 29, 2009 #5

    mathman

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    You need to define p(t|y).
     
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