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Mr M's OCR (not OCR MEI) Core 3 Answers June 2012 Watch

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    Mr M's OCR (not OCR MEI) Core 3 Answers June 2012


    1. x<\frac{4}{3} and x>6 (5 marks)


    2. (i) Show 261 (3 marks)

    (ii) 361 (3 marks)


    3. (i) Show tan theta = 6 (3 marks)

    (ii) (a) \frac{5}{7} (2 marks)

    (b) -\frac{12}{35} (2 marks)


    4. (a) Show integral = 24 (4 marks)

    (b) \frac{e^2+8e-1}{2} (4 marks)


    5. (i) Show one real root (3 marks)

    (ii) (a) 3 and 4 (3 marks)

    (b) 3.24 (4 marks)


    6. (i) 12.17 (4 marks)

    (ii) 0.183 cubic metres per hour (3 marks)


    7. a = 4 and x = -0.5 (7 marks)


    8. (i) 5 \sin (\theta + 53.1301) (3 marks)

    (ii) (a) -64.7 degs and 138 degs (4 marks)

    (b) k = 8 and c = 3 (4 marks)


    9. (i) Show derivative (3 marks)

    (ii) \frac{\pi (3e^4 + 1)}{2} (6 marks)

    (iii) \frac{\pi (e^4 -1)}{2} (2 marks)
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    thanks again!
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    Thanks
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    Mr M, for question 9(ii) for some reason I differentiated ln(2y) instead of integrating (I was trying to integrate but I was just being retarded), and got my answer from there. Will I get a mark?

    EDIT: Btw thanks a lot for the solutions!
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    Mr M 4(b) I accidently messed up when multiplying out the brackets but integrated the terms are everything fine - how many marks would I get for that?

    hope the after school meeting was...fun?
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    Oh and would it be okay for 4(b) to give my answer as e(0.5e+4)-0.5? Thanks
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    (Original post by tahseen1995)
    Mr M, for question 9(ii) for some reason I differentiated ln(2y) instead of integrating (I was trying to integrate but I was just being retarded), and got my answer from there. Will I get a mark?

    EDIT: Btw thanks a lot for the solutions!
    I can't say from what you have told me - it doesn't sound hopeful!
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    How many marks would I drop if I put 4/3 < x < 6 for q1
    , and for using g^1(x) instead of g(x) for the second part of 7?
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    (Original post by tahseen1995)
    Oh and would it be okay for 4(b) to give my answer as e(0.5e+4)-0.5? Thanks
    yes
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    (Original post by Mr M)
    Mr M's OCR (not OCR MEI) Core 3 Answers June 2012
    Mr. M, for 9ii) (the 6 mark question), I did everything correctly up till the point where we had to calculate the lower bound. For some reason, because i'm a dog I differentiated rather than just plugging x=0 into f(x), hence I integrated with lower bound 1, instead of lower bound 1/2. All the steps in the integration were correct, but my final answer would be wrong since the lower limit I subbed in was wrong. How many marks would I lose in your opinion?
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    (Original post by Doctor.)
    Mr M 4(b) I accidently messed up when multiplying out the brackets but integrated the terms are everything fine - how many marks would I get for that?

    hope the after school meeting was...fun?
    It was mercifully brief. I did maths and pretended to listen.

    probably 2 marks
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    I can't remember what I put for 4b, can anyone remember the question? Thanks.
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    (Original post by Tukazoar)
    How many marks would I drop if I put 4/3 < x < 6 for q1
    , and for using g^1(x) instead of g(x) for the second part of 7?
    drop 1 mark and drop 3 marks probably
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    (Original post by Mr M)
    I can't say from what you have told me - it doesn't sound hopeful!
    What I meant is I correctly rearranged the equation to get pi times the integral of y=ln(2x) with limits of 1/2e^(4) and 1/2, but instead of using part (i) of question 9 to find the integral of ln(2x) I integrated ln(2x) to 1/x (I panicked due to lack of time) and went from there.

    I was wondering if would at least get a mark for correctly rearranging the equation and realising the the area of the shaded region rotated about the y axis would be the integral of ln(2x) within limits of 1/2e^(4) and 1/2 multiplied by pi.

    ...did I make sense?

    lol thank you
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    I'm off home now but will answer some more questions later (in about one hour).
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    (Original post by Doctor.)
    Mr M 4(b) I accidently messed up when multiplying out the brackets but integrated the terms are everything fine - how many marks would I get for that?

    hope the after school meeting was...fun?

    (Original post by tahseen1995)
    Mr M, for question 9(ii) for some reason I differentiated ln(2y) instead of integrating (I was trying to integrate but I was just being retarded), and got my answer from there. Will I get a mark?

    EDIT: Btw thanks a lot for the solutions!
    Is this your actual teacher? Seems a bit weird but I suppose it's a good idea too.
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    for 4b i put e^x2 and not 2x. hw much wud i lose and for the last i intergraded put the the y values. ie e^4 one in but got soma dfferent. like 2pi e^4. i also integrated the line and wrkd that out?
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    (Original post by Junaid96)
    Is this your actual teacher? Seems a bit weird but I suppose it's a good idea too.
    Maybe :ninja:

    Just kidding, nope but I do casually stalk Mr M (Only on TSR lol) would be so weird if someone did that in real life :lol:
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    How many marks would I lose for getting

    k = 3/5
    c = 40

    Because I read the question as 37 not MINUS 37!
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    (Original post by Mr M)
    Mr M's OCR (not OCR MEI) Core 3 Answers June 2012

    Thanks. Just two questions.

    On question 9iii) if I used my answer from question 9ii) to calculate the volume (but followed the correct method) would I get any of the 2 marks?

    Also, on question 9ii) I got an incorrect answer as when I substituted in the limits I rewrote ln(e^4) as e^4 instead of 4. However, I applied the limits correctly to the other variables. (And applied the correct method throughout) How many marks out of the 6 is this likely to have costed me?

    Thanks a lot
 
 
 
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