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AQA Core 4 - Monday 10th June 2013 (AM) - Official Thread Watch

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    (Original post by Relf)
    62raw for 90ums?
    Sounds about right.
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    (Original post by Relf)
    62raw for 90ums?
    I'd personally go 60 for 90 and 67 for 100, but we're just guessing really.
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    (Original post by fizzbizz)
    a)  \int t cos(\frac{\pi}{4}t) dt

    u = t \Rightarrow u'=1

    v' = cos(\frac{\pi}{4}t) \Rightarrow v = \frac{4}{\pi}sin(\frac{\pi}{4}t)

    \int = uv - \int vu' dt= \frac{4}{\pi}tsin(\frac{\pi}{4}t  ) - \int \frac{4}{\pi}sin(\frac{\pi}{4}t) dt+c

     \frac{4}{\pi}tsin(\frac{\pi}{4}t  ) + \frac{16}{\pi^2}cos(\frac{\pi}{4  }t)+c



    b) \frac{dx}{dt}= \frac{t cos(\frac{\pi}{4}t)}{32x}

    \int x dx = \frac{1}{32} \int  t cos(\frac{\pi}{4}t) dt

    \frac{x^2}{2} = \frac{1}{32}[\frac{4}{\pi}tsin(\frac{\pi}{4}t  ) + \frac{16}{\pi^2}cos(\frac{\pi}{4  }t)+c]

    \frac{x^2}{2} = \frac{1}{8\pi}tsin(\frac{\pi}{4}  t) + \frac{1}{2\pi^2}cos(\frac{\pi}{4  }t)+c

    Sub in x = 4 and t = 0;

    8 = \frac{1}{2\pi^2} + c \Rightarrow c = 8 - \frac{1}{2\pi^2}

    So:

    \frac{x^2}{2} = \frac{1}{8\pi}tsin(\frac{\pi}{4}  t) + \frac{1}{2\pi^2}cos(\frac{\pi}{4  }t)+8 - \frac{1}{2\pi^2}

    When t = 45 (type it into your calculator carefully);

    \frac{x^2}{2} = 6.647

    x^2=13.295

    x = 3.646 \Rightarrow x = 3.65m or 365cm to the nearest cm
    If I did everything else completely right but I did the by parts question wrong then used that result in the next question, how many marks would I get out of a total of 10?
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    Turned to question 7, saw that it was only one question for 3 marks and I thought that I'd lost a page in the question booklet.
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    Does anyone have the paper so they can upload it? Noticed someone did this for the Core 3 paper.
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    (Original post by joe900)
    Right Guys;
    Lets get real for a minute -
    Predicted grades for C4 and C3 please- Not what we hope but what we actually think PLEASE

    For what its worth I thought C4 today was TERRIBLE but I see most seem to be getting many correct answers - hence its better for me to realistic about what I will get - I reckon I have 40 RAW MARKS
    Please could I have some replies - Tks a mill:confused:
    Well Core 3 I originally got 1 mark off an A, I retook that exam and I felt a lot better about it so around 90% (A), then even though Core 4 was ridiculous I still feel that it went really well and again I'm looking around 90%.
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    (Original post by Relf)
    62raw for 90ums?
    I feel so pessimistic right now i hope it's that Low or even lower but I doubt it if lots of people were getting answers right
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    Predicted Grade Boundaries?

    What u think?
    C4 - 55 A , 49B, 43C, 38D?
    C3 - 65A, 59B, 54C, 48D?
    D1- 65A, 60B, 55C, 50D?
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    (Original post by mulac1)
    I've just looked back at my predictions for the C3 paper in January and I underestimated the boundaries by 3 marks!... so heres my 'revised' guess:

    CAP = 71
    A* = 64
    A = 57
    B = 52
    C = 47
    D = 42
    E = 37
    U = <32
    Id say that each grade is at least 2 marks too high
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    (Original post by mulac1)
    I've just looked back at my predictions for the C3 paper in January and I underestimated the boundaries by 3 marks!... so heres my 'revised' guess:

    CAP = 71
    A* = 64
    A = 57
    B = 52
    C = 47
    D = 42
    E = 37
    U = <32
    I can't personally see this exam being 5 marks easier than the paper in January!
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    From what I've seen the grade boundaries are usually separated by 5 raw marks in the past.

    I think:

    100UMS: 66
    A* 61
    A 56
    B 51

    these are 3 higher than the january c4 boundaries.

    I think I got 65. Maybe more if I can find out if I didn't completely miss out 2 marks on a question I didn't see.
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    (Original post by mulac1)
    I've just looked back at my predictions for the C3 paper in January and I underestimated the boundaries by 3 marks!... so heres my 'revised' guess:

    CAP = 71
    A* = 64
    A = 57
    B = 52
    C = 47
    D = 42
    E = 37
    U = <32
    the boundaries go up at a linear rate. yours change from 7, 7, 5, 5 etc, they will all be of the same gap, e.g 5 or 6.
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    true..

    CAP = 69
    A* = 64
    A = 59
    B = 53
    C = 48
    D = 43
    E = 38
    U = <33
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    thats 6 marks higher than Jan13 - I'd say I'm erring on the side of caution
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    (Original post by mulac1)
    thats 6 marks higher than Jan13 - I'd say I'm erring on the side of caution
    Yeah, I put mine as 3 raw marks higher than January 2013. Some of the papers with A* around 64 were way easier than today's paper of January's.
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    Does anyone know if I'll get ecf marks for the last question (I integrated using 1/4 instead of pi/4 by accident) ?


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    I guess the paper wasn't so much hard overall, as just highly weighted towards the tough questions.
    Which does by definition make it seem harder as you drop more marks,this will invariably affect the lower grade bds.

    Also there were a lot of linked questions, 1a and 1b were used in 1c for instance, which would have confused some candidates.

    Certainly I personally found the exam quite hard though towards the end,but maybe this was uniform for people of my ability.

    I think:

    100 UMS:70 (Sadly can't see it being lower than this)
    A* 61
    A 56
    B 51
    C 46
    D 41

    I reckon I've dropped around 22-24 marks, so overall I believe I've achieved a B which is not too bad , but I really did want an A really,ahh well 3 exams to go!
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    (Original post by Sciencephile)
    I did, but its 3.65- kept my calculator in degrees instead of changing back to radians, youve probably done the same. Reckon we'll only lose one mark for that though as all the working out was right
    WOOOO stupid mistakes! I just realised I did this too :doh: I hope you're right about the 1 mark loss, I have no idea what to think of the entire thing! They didn't do any big chunky questions just lots of medium ones, I mean where was the implicit?!
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    (Original post by annaridgway95)
    Does anyone know if I'll get ecf marks for the last question (I integrated using 1/4 instead of pi/4 by accident) ?


    Posted from TSR Mobile
    If you put the correct method down,you should get follow through marks.

    Probably not too many in the first instance,but for the second part if you integrated and got 16x^2 = "what you integrated",then put in t=0 and found your value of C i'd think you'd pick up 1/4 and 3/6 of the marks if they are feeling nice on the mark scheme.

    For the very first part it all depends whether you got the correct values for du/dx and v using integration by parts

    I used substitution for some unknown reason and once again messed it up think you had to use int by parts sadly
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    (Original post by KING2011BOB)
    If you put the correct method down,you should get follow through marks.

    Probably not too many in the first instance,but for the second part if you integrated and got 16x^2 = "what you integrated",then put in t=0 and found your value of C i'd think you'd pick up 1/4 and 3/6 of the marks if they are feeling nice on the mark scheme.

    For the very first part it all depends whether you got the correct values for du/dx and v using integration by parts

    I used substitution for some unknown reason and once again messed it up think you had to use int by parts sadly
    Meh ok, well I hope you're right, can't believe I didn't notice the pi :/ hate myself right now. And ahh right did you get a different answer then or not?


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