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    (Original post by economicss)
    Sorry, it shouldn't be, is from solutions bank It's exercise 3E question 13b on page 44 of the textbook Thanks
    This is. The working I was trying to show
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    (Original post by economicss)
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    This is. The working I was trying to show
    Zacken
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    (Original post by economicss)
    Zacken
    So you got z=1.43, this means your confidence interval is the area between -1.43 and 1.43, no?
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    (Original post by Zacken)
    So you got z=1.43, this means your confidence interval is the area between -1.43 and 1.43, no?
    Ah yes, should have used the diagram!! Thanks!
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    (Original post by economicss)
    Ah yes, should have used the diagram!! Thanks!
    Nice! Glad that little hint helped. :-)
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    (Original post by Zacken)
    Nice! Glad that little hint helped. :-)
    You're a lifesaver!
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    (Original post by economicss)
    You're a lifesaver!
    No problem. Do you want to tag me on that FP2 thingy you were asking me about earlier so I can have a look at it (not right now because I'm not home) but when I'm back?
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    (Original post by Zacken)
    No problem. Do you want to tag me on that FP2 thingy you were asking me about earlier so I can have a look at it (not right now because I'm not home) but when I'm back?
    Yeah that would be great, thank you
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    (Original post by economicss)
    Yeah that would be great, thank you
    Thanks!
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    Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)
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    (Original post by economicss)
    Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)
    Please link the paper or a picture of the question
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    (Original post by economicss)
    Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)
    I haven't seen the question because I'm saving that paper as a mock but are you aware (from S1 and S3) that \text{Var}(aX) = a^2\text{Var}(X) and E(ax) = aE(X) so that \text{Var}(\frac{X}{2}) = \left(\frac{1}{2}\right)^2\text{  Var}(X) = \frac{1}{4}\text{Var}(X)?
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    (Original post by economicss)
    Hi please could someone explain question 2b of the june 2014 paper, why is it we divide by 2 squared for the variance rather than 2? Thanks :-)
    I've actually done this question on a mock - you should follow techniques learnt in S1 that Zacken mentioned and it's simple from there.
    Spoiler:
    Show
    \displaystyle \mathrm{Var}\left ( \frac{3X_{1}-X_{20}}{2} \right ) = \frac{1}{4}\mathrm{Var}\left ( 3X_1-X_{20} \right ) = \cdots
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    (Original post by aymanzayedmannan)
    I've actually done this question on a mock - you should follow techniques learnt in S1 that Zacken mentioned and it's simple from there.
    Spoiler:
    Show
    \displaystyle \mathrm{Var}\left ( \frac{3X_{1}-X_{20}}{2} \right ) = \frac{1}{4}\mathrm{Var}\left ( 3X_1-X_{20} \right ) = \cdots
    Thanks so much, should have taken the 1/2 outside of it! Please could you explain how question 6c on this paper https://869d950bf149eefd5cd2652b4001...%20Edexcel.pdf is done using confidence intervals, as I understand the normal distribution method but not too sure how it can be solved using confidence intervals? Thanks
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    Hi, does anyone know please whether we could be asked to do a test like that one in question 4i here? From an OCR paper https://f1f559d498e385d34687bce0088e...20S3%20OCR.pdf
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    (Original post by economicss)
    Hi, does anyone know please whether we could be asked to do a test like that one in question 4i here? From an OCR paper https://f1f559d498e385d34687bce0088e...20S3%20OCR.pdf
    I think this is out of spec. I'm not certain though.
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    (Original post by economicss)
    Hi, does anyone know please whether we could be asked to do a test like that one in question 4i here? From an OCR paper
    Nope, the only continuous distribution we work with is the normal and uniform, not random PDF's like those. You could, however be given a continuous uniform PDF and asked to find the expected frequency though, it's not really that different.
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    Does anyone know if there's any extra resources available for this module, like practice papers? Thanks
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    (Original post by economicss)
    Does anyone know if there's any extra resources available for this module, like practice papers? Thanks
    Have you done the book's review exercises?
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    (Original post by aymanzayedmannan)
    Have you done the book's review exercises?
    Yeah
 
 
 
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