C3 Mei Coursework Mark Scheme Igcse

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  1. 12/3/18 Update: I, as per forum rules, will not be distributing the papers I acquired after my exams. However, if people sat them for a mock or otherwise attained them, and would like some worked examples I'd be more than happy to help if you send me a PM, granted I can find the papers when i return home from Uni at the end of this term (27/3/18).

    Might not be 100% accurate - if you disagree post below!

    1.) 12x^2/(5-2x^3)^3 [^-3 if you left as times, I made it a division, so it's over ^3.]

    2.) Triangle graph: (-1,0), (0,2), (1,0) (I think going beyond bounds might be penalized, but i'm not sure, as f(x) was only defined for -1<x<1)

    3.) f^-1(x) = 1-e^(x), domain: x<ln(2), range: -1<y<1
    ii) f(x)+f(-x) = ln(1-x^2) = fg(x) [show that]

    4) dy/dx = (-3y^(2/3))/(x^1/3)
    ii) m = -12

    5) initial temp: 10.5, boiling point: 80
    ii) k=0.329
    iii) 13 minutes

    6) 180(n-2)=155n, => n =14.xx so not an integer therefore can't work
    OR exhaustion with n=14=154 and n=15=156 so can't be 155 for an integer, n
    OR All exterior angles add up to 360. An interior angle of 155 would mean an external angle of 25 which is not a factor of 360

    7) x=2sin(y), dx/dy = 2cos(y)
    ii) 2(rt3)/3

    8) A(pi/2,0) C(0,1/2)
    ii) dy/dx= (1-2sinx)/(2-sinx)^2, B=(pi/6,rt3/3)
    iii A) area = ln2
    iii B) [ln(2-sinx)]between(k and 0) = [ln(2-sinx)]between(pi/2 and k), show k=(arcsin(2-rt2)) via rearrangement:
    Some people i've spoken to don't get what this means, so workings at bottom!

    9) f(-x) = -f(x) so odd, y=f(x) has rotational symmetry order 2 about origin
    ii) stationary points: (0,0) (1.22,0.41), (-1.22,-0.41) (it wanted to 2dp for y, x can be either based on past papers with the "where appropriate" bit).
    iii) correct graph from x=-2 to x=2.
    iv A) integral(1/2te^-t)
    iv B) area = 0.5 - (5/2)(e^-4)

    C4 - https://www.thestudentroom.co.uk/sho....php?t=4799506

    workings:

    https://gyazo.com/26986dd9b6b890551eaaa340818bc96f
  2. Thank you for sharing

    Fox Corner Tagged to add to unofficial markscheme list

Writing on The Student Room website, one student said: “They should definitely give us a re-sit. There's no fair way to mark that paper.”

Another said: “Even if you do remove the question, most people will still not achieve the grade they deserve.

“I spent 20 minutes on that question (as it was worth the most marks) and had to rush everything else. I really needed to get an A and now I am scared I won’t even get a B.”

The error centred around a 90-minute “decision mathematics” AS-level exam sat by students in 335 schools and colleges. AS-levels are normally sat in the first year of two-year A-level courses.

In the final section, students were presented with a diagram showing a network of tracks in a forest. The distances between points on the network were also set out.

One question worth eight marks – more than 11 per cent of the total exam – asked students to find the shortest route to walk along every track, starting and ending at the same point. The given length was supposed to be equal to an equation set out in the test paper.

But the exam board admitted that it failed to calculate the length properly – meaning the shortest route failed to match their mathematical equation.

An OCR spokeswoman said the exam board regretted the mistake “and that our quality assurance procedures failed to identify this error”.

“We would like to assure teachers, parents and students that we have several measures in place to ensure that candidates are not unfairly disadvantaged as a result of this unfortunate error,” she said.

“Because we have been alerted to this so early, we are able to take this error into account when marking the paper. We will also take it into account when setting the grade boundaries.”

She added: “To help us understand how this occurred and to minimise the chance of such an error happening again, we will be undertaking a thorough review of our quality assurance procedures."

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