OCR MATHEMATICS C3 (Monday 2nd June 2008)

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  1. FXX's Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    woot, failed that one too Now I've just got M1 to **** up on on Friday and I'll be set for a U!
  2. Paper Planes's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    q1 modulus sign incorrect. should be x not mod x =)
  3. Gancor's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by gaomeister)
    Latex rocks :P

    1)  |x| \ = \ 0
    x \ = \ \frac {10}{7} (4 marks)

    2) (i)  y \ = \ f^{-1}(x) crosses axes at (0,-3) and (2,0) (2 marks)

    (ii)  y \ = \ -2 f(x) crosses axes at (-3,0) and (0,-4) (3 marks)

    3) Tangent  y \ = \ 3ex \ - \ 2e^2 (6 marks)

    4) (i) Show x coord of P (3 marks)

    (ii) Show between 0.3 and 0.4 (sign change) (3 marks)

    (iii)  x \ = \ 0.3553 (4 dp) You needed to show each iteration (3 marks)

    5) (a)  tan 2a \ = \ \frac {2tan \alpha}{1 - tan^2 \alpha}
     \alpha \ = \ 41.8^{\circ} or 138^{\circ} (6 marks)

    (b) (i)  cosec \beta \ = \ \frac{7}{6} (1 mark)

    (ii)  cot^2 \beta \ = \ \frac {13}{36} (2 marks)

    6) Volume \  = \ \frac {\pi}{18} (3e^3 - 4) (9 marks)

    7) (i)  N \ = \ 42
     k \ = \ \frac {1}{9}
     m \ = \ \frac {ln 2}{9} (4 marks)

    (ii)  t \ = \ 11.3 years (2 marks)

    (iii)  \frac {dN}{dt} \ = \ 47.9 plants per year (3 marks)

    8) (i)  A \ = \ \sqrt \frac {3}{2}
     \beta \ = \ \frac {5}{2} (3 marks)

    (ii)  R \ = \ \sqrt 7
     \alpha \ = \ 70.9^{\circ} (3 marks)

    (iii) \theta \ = \ 131^{\circ} (4 marks)

    9) i)  Range \ 0 \ \leq \ f(x) \ \leq \ \frac {3 sqrt 5}{2} (6 marks)

    ii)  k \ = \ sqrt 5 (1 mark)

    iii) Show grad cannot equal -1 (discriminant is easiest way) (4 marks)
    Oh hai will you marry me?
  4. rasmusrok1's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    Mr M a quick question: on question 7. if i got all the limits wrong (i know stuped mistakes) but carry on and correctly do teh part ii and iii will i get the marks for them as in error carried foreward? Please answer i'm agonising over this!

    Thanks so much for the answers we needed some definitive ones!
  5. wizz_kid's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    in the volumes of revolution question, i incorrectly wrote  (e^3^x)^2 as e^9^x^2 (e to the 9 x^2)

    the rest of the working is rite. How many marks would i get?
  6. Elle Jeffrey's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by Mr M)
    Here's the answers for OCR Core 3:

    1) Modulus x= 0 x = 10/7 (4 marks)

    2) (i) y = f^-1(x) crosses axes at (0,-3) and (2,0) (2 marks)

    (ii) y = -2f(x) crosses axes at (-3,0) and (0,-4) (3 marks)

    3) Tangent y = 3ex - 2e^2 (6 marks)

    4) (i) Show x coord of P (3 marks)

    (ii) Show between 0.3 and 0.4 (sign change) (3 marks)

    (iii) x = 0.3553 (4 dp) You needed to show each iteration (3 marks)

    5) (a) tan 2a = 2tana/(1 - tan^2 a)
    a = 41.8 degs or 138 degs (6 marks)

    (b) (i) cosec B = 7/6 (1 mark)

    (ii) cot^2 B = 13/36 (2 marks)

    6) Volume = pi/18 (3e^3 - 4) (9 marks)

    7) (i) N = 42 k = 1/9 m = (ln 2)/9 (4 marks)

    (ii) t = 11.3 years (2 marks)

    (iii) dN/dt = 47.9 plants per year (3 marks)

    8) (i) A = root 3/2 B = 5/2 (3 marks)

    (ii) R = root 7 a = 70.9 degs (3 marks)

    (iii) Theta = 131 degs (4 marks)

    9) i) Range 0 <= f(x) <= 3 root 5 /2 (6 marks)

    ii) k = root 5 (1 mark)

    iii) Show grad cannot equal -1 (discriminant is easiest way) (4 marks)

    Give me half an hour to get something to eat and I will do FP1.
    You have just made me very happy! =D
  7. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by hasnain721)
    in the volumes of revolution question, i incorrectly wrote  (e^3^x)^2 as e^9^x^2 (e to the 9 x^2)

    the rest of the working is rite. How many marks would i get?
    If everything else was ok, I expect you would drop 2 marks.
  8. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    [QUOTE=gaomeister]Latex rocks :P

    QUOTE]

    Gaomeister, fancy going over to my answers on the FP1 thread and making them look beautiful?

    I keep meaning to learn to use latex but never quite get round to it!
  9. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by rasmusrok1)
    Mr M a quick question: on question 7. if i got all the limits wrong (i know stuped mistakes) but carry on and correctly do teh part ii and iii will i get the marks for them as in error carried foreward? Please answer i'm agonising over this!

    Thanks so much for the answers we needed some definitive ones!
    Question 7 doesn't have limits! Do you mean 6?
  10. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by Paper Planes)
    q1 modulus sign incorrect. should be x not mod x =)
    That wasn't meant to be modulus x! It was meant to mean: modulus question x = 0 x = 10/7 so people remembered what it was!
  11. gaomeister's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    [QUOTE=Mr M]
    (Original post by gaomeister)
    Latex rocks :P

    QUOTE]

    Gaomeister, fancy going over to my answers on the FP1 thread and making them look beautiful?

    I keep meaning to learn to use latex but never quite get round to it!
    I'd love to, but I've never done FP1 so I don't really know how their meant to look
  12. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    [QUOTE=gaomeister]
    (Original post by Mr M)

    I'd love to, but I've never done FP1 so I don't really know how their meant to look
    Ah ok don't worry!
  13. Sky Twilight's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    Q6) If I forgot to square, and put pi, in volumes of revolution -
    BUT i minused the integral of curve A from B .. what would I get?

    and last question, do you think I'd get a mark for writing discriminant?

    Btw, whats the total out of?
  14. TC46's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    Mr M, with regards to question 6 stupidly i made ((e^3x)^2) = e^5x but i think i carried through with the rest of the question, can you hazard a guess as to how many marks i could get?

    cheers
  15. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by Sky Twilight)
    Q6) If I forgot to square, and put pi, in volumes of revolution -
    BUT i minused the integral of curve A from B .. what would I get?

    and last question, do you think I'd get a mark for writing discriminant?

    Btw, whats the total out of?
    This made me smile (sorry!) - if you didn't square or put pi in, you didn't exactly find the volume did you?!

    The question was worth 9 marks, maybe an attempt to integrate between 0 and 0.5 would be worth 1 and subtracting would be worth 1. I'm struggling to give you more than 2 but there might be a mark for the manipulation of your answer.

    Possibly one mark for writing discriminant.

    Total is out of 72.
  16. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by TC46)
    Mr M, with regards to question 6 stupidly i made ((e^3x)^2) = e^5x but i think i carried through with the rest of the question, can you hazard a guess as to how many marks i could get?

    cheers
    Ah that old classic 3 x 2 = 5.

    Drop two marks for accuracy.
  17. lauuuura's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    Mr M,
    I know everyone is asking you lots of 'how many marks will i get for...' questions, but just one more!
    In question 6, for some reason I integrated the second function, and took away a power instead of adding it - the rest i think i got right? Roughly how many do you think i might lose?!

    Thankyou - rep on its way!
  18. Blackwater's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    Can anyone remember what the first question was exactly? Somehow I got x=0 and x=2...
  19. rasmusrok1's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    sorry i did mean question 7 but i meant the values for k m and A...
    thanks mr M
  20. Mr M's Avatar
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    Re: OCR MATHEMATICS C3 (Monday 2nd June 2008)
    (Original post by rasmusrok1)
    sorry i did mean question 7 but i meant the values for k m and A...
    thanks mr M
    Yes if you did part (i) wrong you could get some credit in (ii) and (iii) for using the error carried forward. You would lose at least one mark in (ii) and (iii) for accuracy.
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