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Edexcel A2 C4 Mathematics June 2016 - Official Thread Watch

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    (Original post by GeologyMaths)
    Stupid errors like

    

\dfrac{1}{3} \dfrac{-1}{3}
    au lieu of
    

\dfrac{1}{3} \dfrac{-2}{3}

basically since 1/2-1 = -1/2, i think 1/3-1=-1/3
    Ouch I see.. that's not an easy one to fix I guess, apart from plugging in nice values of x to check that the expansion is roughly equal to the exact value.
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    Hi, does anyone know if there is a January 2015 IAL S2 paper ?
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    (Original post by Danllo)
    Hi, does anyone know if there is a January 2015 IAL S2 paper ?
    http://qualifications.pearson.com/co...e_20150122.pdf
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    (Original post by kingaaran;[url="tel:63518189")
    63518189[/url]]http://qualifications.pearson.com/co...e_20150122.pdf
    Thanks you !
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    (Original post by kingaaran;[url="tel:63518189")
    63518189[/url]]http://qualifications.pearson.com/co...e_20150122.pdf
    Thank you !
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    All of you geniuses already started doing past papers & I'm not even finished the course wait for me loool
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    Does anyone do D1? How are you finding it?
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    (Original post by KINGYusuf)
    All of you geniuses already started doing past papers & I'm not even finished the course wait for me loool
    C3,C4, yeah? How much do you have left? It's getting kinda late, isn't it?
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    (Original post by KINGYusuf)
    All of you geniuses already started doing past papers & I'm not even finished the course wait for me loool
    I still haven't finished, although I've worked ahead of my class. We still haven't done Vectors, Binomial expansion or solving differential equations.
    (Original post by GeologyMaths)
    Does anyone do D1? How are you finding it?
    Haven't revised it in ages, but most of it is straightforward, there are a few tricky bits, like scheduling without doing gantt charts.
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    (Original post by Dohaeris)
    C3,C4, yeah? How much do you have left? It's getting kinda late, isn't it?
    Actually, I think we finished last lesson, I was probs day dreaming then
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    (Original post by KINGYusuf)
    All of you geniuses already started doing past papers & I'm not even finished the course wait for me loool
    We haven't done integration by parts and vectors yet.


    (Original post by NotNotBatman)
    Haven't revised it in ages, but most of it is straightforward, there are a few tricky bits, like scheduling without doing gantt charts.
    How are we even supposed to do that? *shrugs*
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    Is there an s2 thread


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    When I approximate from Binomial to Poisson, Binomial to Normal or Poisson to Normal, do I have to change the letter ("X") to a different letter ("Y") ? For instance, X-B(1000,0.01) would be approximated to a Normal distribution, right ? In the markscheme they would put "N(10,10)".
    Would it be wrong if I put "Y-N(10,10) ?

    Now onto different point. When I Scale up a variable (such as Lamda) do I have to change the letter I first started with ? For example, there are 2 accidents in 1 week so the distribution would be X-Po(2) and I would let X be the random variable the number of accidents. If the question now said in 50 weeks, would I write X-Po(100) or Y-Po(100) ?
    Please could someone help clarify this basic point that I can't seem to get :/
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    (Original post by Danllo)
    When I approximate from Binomial to Poisson, Binomial to Normal or Poisson to Normal, do I have to change the letter ("X" to a different letter ("Y" ? For instance, X-B(1000,0.01) would be approximated to a Normal distribution, right ? In the markscheme they would put "N(10,10)".
    Would it be wrong if I put "Y-N(10,10) ?

    Now onto different point. When I Scale up a variable (such as Lamda) do I have to change the letter I first started with ? For example, there are 2 accidents in 1 week so the distribution would be X-Po(2) and I would let X be the random variable the number of accidents. If the question now said in 50 weeks, would I write X-Po(100) or Y-Po(100) ?
    Please could someone help clarify this basic point that I can't seem to get :/
    In the first case, usually I wouldn't bother to change the variable. Perhaps make it clear it's an approximation. But I also doubt you would lose marks if you said you were approximating X by the variable Y with that distribution, so long as at the end you give your approximate answer in terms of X.

    In the second case, I probably would change the name (and say what you're doing and what exactly the new variable is).
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    (Original post by 13 1 20 8 42)
    In the first case, usually I wouldn't bother to change the variable. Perhaps make it clear it's an approximation. But I also doubt you would lose marks if you said you were approximating X by the variable Y with that distribution, so long as at the end you give your approximate answer in terms of X.
    My stats teacher told me that we have to change the variable for your approximation. So suppose you have X ~ B(1000, 0.01), \displaystyle X\sim \mathrm{B}\left ( 1000, 0.01 \right ) \Longleftrightarrow X\approx Y \sim\mathrm{Po}\left ( 1 \right ). :dontknow: He even cut marks for not "renaming" the variable. It gets very annoying having multiple variables denoted by different letters.

    Maybe someone can correct me here?
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    (Original post by aymanzayedmannan)
    My stats teacher told me that we have to change the variable for your approximation. So suppose you have X ~ B(1000, 0.01), \displaystyle X\sim \mathrm{B}\left ( 1000, 0.01 \right ) \Longleftrightarrow X\approx Y \sim\mathrm{Po}\left ( 1 \right ). :dontknow: He even cut marks for not "renaming" the variable. It gets very annoying having multiple variables denoted by different letters.

    Maybe someone can correct me here?
    I didn't and it all turned out fine - but tiny hobbit also suggested the change of variable too, so I'd go with that.

    What I used to do was X \sim B(1000, 0.01) \Rightarrow X \approx \mathrm{Po}(1)
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    Are there any new papers on the crash maths website yet ?
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    (Original post by Danllo)
    When I approximate from Binomial to Poisson, Binomial to Normal or Poisson to Normal, do I have to change the letter ("X") to a different letter ("Y") ? For instance, X-B(1000,0.01) would be approximated to a Normal distribution, right ? In the markscheme they would put "N(10,10)".
    Would it be wrong if I put "Y-N(10,10) ?

    Now onto different point. When I Scale up a variable (such as Lamda) do I have to change the letter I first started with ? For example, there are 2 accidents in 1 week so the distribution would be X-Po(2) and I would let X be the random variable the number of accidents. If the question now said in 50 weeks, would I write X-Po(100) or Y-Po(100) ?
    Please could someone help clarify this basic point that I can't seem to get :/
    (Original post by 13 1 20 8 42)
    In the first case, usually I wouldn't bother to change the variable. Perhaps make it clear it's an approximation. But I also doubt you would lose marks if you said you were approximating X by the variable Y with that distribution, so long as at the end you give your approximate answer in terms of X.

    In the second case, I probably would change the name (and say what you're doing and what exactly the new variable is).
    (Original post by aymanzayedmannan)
    My stats teacher told me that we have to change the variable for your approximation. So suppose you have X ~ B(1000, 0.01), \displaystyle X\sim \mathrm{B}\left ( 1000, 0.01 \right ) \Longleftrightarrow X\approx Y \sim\mathrm{Po}\left ( 1 \right ). :dontknow: He even cut marks for not "renaming" the variable. It gets very annoying having multiple variables denoted by different letters.

    Maybe someone can correct me here?
    (Original post by Zacken)
    I didn't and it all turned out fine - but tiny hobbit also suggested the change of variable too, so I'd go with that.

    What I used to do was X \sim B(1000, 0.01) \Rightarrow X \approx \mathrm{Po}(1)
    It wouldn't matter as far as marks go (I'm talking Edexcel here). The important thing is that you are clear as to which variable you are using at any given moment and what its distribution is. If using a different letter keeps it clear for you, then that's a good thing.
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    (Original post by tiny hobbit)
    It wouldn't matter as far as marks go (I'm talking Edexcel here). The important thing is that you are clear as to which variable you are using at any given moment and what its distribution is. If using a different letter keeps it clear for you, then that's a good thing.
    Thank you!

    I have another (possibly silly) question: on the paper, you're always asked to state your hypotheses clearly. Does this make it alright to just simply state p= 0.25 or do we have to write everything out in words?
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    (Original post by aymanzayedmannan)
    Thank you!

    I have another (possibly silly) question: on the paper, you're always asked to state your hypotheses clearly. Does this make it alright to just simply state p= 0.25 or do we have to write everything out in words?
    You need to say (e.g.)

    H0: p = 0.25
    H1: p > 0.25 (or whatever the inequality is)

    Similar pattern for Poisson, replacing p with lambda
 
 
 
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