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    Can someone explain what the mark scheme has done i don't get it.

    Why have the multiplied 50/49 by s^2? For sigma^2?

    Thanks
    http://m.imgur.com/QovjnOS,5RN8ML6,ZqxWmVv
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    (Original post by Super199)
    Can someone explain what the mark scheme has done i don't get it.

    Why have the multiplied 50/49 by s^2? For sigma^2?

    Thanks
    http://m.imgur.com/QovjnOS,5RN8ML6,ZqxWmVv
    It'd be lovely if you could give us the question as well...
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    (Original post by Zacken)
    It'd be lovely if you could give us the question as well...
    Scroll down, question 6.
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    (Original post by Zacken)
    It'd be lovely if you could give us the question as well...
    q6 babe sorry x
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    (Original post by EricPiphany)
    Scroll down, question 6.
    (Original post by Super199)
    q6 babe sorry x
    Sorry, didn't scroll down.
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    (Original post by Super199)
    Can someone explain what the mark scheme has done i don't get it.

    Why have the multiplied 50/49 by s^2? For sigma^2?

    Thanks
    http://m.imgur.com/QovjnOS,5RN8ML6,ZqxWmVv
    The markscheme's just making use of the fact that your sample variance is \displaystyle \frac{\sum (x_i - \bar{x})^2}{n-1} in a different way.
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    (Original post by Zacken)
    The markscheme's just making use of the fact that your sample variance is \displaystyle \frac{\sum (x_i - \bar{x})^2}{n-1} in a different way.
    Yh but I dont get 2.1?
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    (Original post by Super199)
    Yh but I dont get 2.1?
    s^2 = \frac{\sum w^2 - \frac{1}{50} (\sum w)^2}{50-1}, what does that get you?
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    (Original post by Zacken)
    s^2 = \frac{\sum w^2 - \frac{1}{50} (\sum w)^2}{50-1}, what does that get you?
    50/49? g
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    (Original post by Super199)
    50/49? g
    Yeaaah, that's the correct answer.
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    (Original post by Zacken)
    Yeaaah, that's the correct answer.
    Yh mate that wasn't the issue. Issue was the z value how do you get 2.1?
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    (Original post by Super199)
    Yh mate that wasn't the issue. Issue was the z value how do you get 2.1?
    \displaystyle z = \frac{x - \bar{x}}{\frac{\sigma}{\sqrt{n}}  }
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    (Original post by Zacken)
    \displaystyle z = \frac{x - \bar{x}}{\frac{\sigma}{\sqrt{n}}  }
    Ah right yh got it.
    Do you mind helping me with another.

    I dont get when you do C-80 or 80-C? On the top. Like they have done 80-C in this case. Thanks
    Q7i

    http://m.imgur.com/KaaeSRH
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    (Original post by Zacken)
    \displaystyle z = \frac{x - \bar{x}}{\frac{\sigma}{\sqrt{n}}  }
    I hope we don't have to know these formulae for Edexcel, because I haven't seen them lol
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    (Original post by EricPiphany)
    I hope we don't have to know these formulae for Edexcel, because I haven't seen them lol
    It's S3 for us.
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    (Original post by Super199)
    Ah right yh got it.
    Do you mind helping me with another.

    I dont get when you do C-80 or 80-C? On the top. Like they have done 80-C in this case. Thanks
    Q7i

    http://m.imgur.com/KaaeSRH
    If I'm understanding you well then: it's P(z<\cdots) means 80-c and P(z > \cdots) then it's c-80
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    (Original post by Zacken)
    It's S3 for us.
    Phew, thanks
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    (Original post by Zacken)
    If I'm understanding you well then: it's P(z<\cdots) means 80-c and P(z > \cdots) then it's c-80
    So are we looking at H1 here? and since it says mu<80? so it's 80-c?. But if it was mu>80 it would be c-80? Or have I got the wrong end of the stick.
 
 
 
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