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Mr M's OCR (not OCR MEI) Core 2 Answers May 2013

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for the last question, I got 4 values, but 3 of my values were the answers. Dont know where the random value came, any ideas on how much marks i'll be able to get?

Reply 61

Mr M

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Original post by kiraeil

What was the working for 5ii) the question on finding the perimeter? Thanks.

Use the cosine rule to find BD= 12.2

Use

s=r \theta

to find the arc BC = 16 x 0.8

Add DC to BC to BD

Reply 62

Mr M

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Original post by eggfriedrice

Thanks Mr M! Looks like I made two stupid mistakes :/

Q3) I put 64+960x +3000x ^2
Q 4) ii a =1/2 (didn't notice the ^- so didn't flip)

How many marks lost?

Drop 1 mark for Q3 and probably 1 mark for Q4.

Reply 63

Mr M

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Original post by milesw97

For question 9)ii) I inspected the cubic correctly to get a linear and a quadratic factor but somehow managed to get the + and - signs the wrong way round when I factorised by quadratic, getting (2x+3)(x-1). How many marks do you think this will cost me? Also, I then carried this error forwards into 9)iii) but used the correct method and got 2 of the 3 answers. Is there an allowance for error carried forwards or will I lose more marks here?

Drop 2 marks on 9 ii) and get full marks on 9 iii) probably.

Reply 64

Mr M

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Original post by CalBeans

I got the value for C as 24 and dont understand how it is -11 can you explain the answer in more detail please?

Well if you work out the coefficient of x you obtain:

8640+384c=4416

Reply 65

Mr M

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Original post by kiraeil

Thanks- If I worked out the missing side and arc length correctly but made a silly mistake for the length of the last side how many marks would i get. Thanks

drop 1 or 2 if you are unlucky

Reply 66

Mr M

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Original post by 5foot

How many marks will I get for the area under the curve if I got the equation of the tangent wrong

Posted from TSR Mobile

you need to provide more information

Reply 67

owl 1996

I put (x+0.5)(2x+2)(2x-3) for 9ii- this multiplies out the same, will i still get the marks? Thanks :smile:

Reply 68

Mr M

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Original post by kiraeil

How many marks do you think I would get if worked area of small triangle and equation of tangent correct- 2 marks?? Thanks

(Original post by kiraeil)
For the area under curve question would I get some marks for workings as i worked out equation of tangent and area of small triangle but got complete wrong answer?
thanks

3 marks

Reply 69

Mr M

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Original post by MR.Mlover

Mr M, i love you, take me back :colondollar:

I've moved on.

Reply 70

HayyanN

Original post by Mr M

Well if you work out the coefficient of x you obtain:

8640+384c=4416

(3*3*960)+(64*6) = 4416 (just to clarify for you) (for MrMlover, not sure why it went to MrM)

(edited 10 years ago)

Reply 71

Mr M

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Original post by Ellie_Rosa

For question 8 i a and b I put y=1 and y=4 instead of coordinates - will I lose the marks?

Unfortunately yes.

Reply 72

Mr M

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Original post by NZK1W1

This went so well :biggrin:

thanks for putting up your answers Mr. M, they were all the same as what i got! :biggrin:

You must be mega-brainy then.

Reply 73

Mr M

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Original post by geekD96

Heeeey for (4b) I never got this (i)

(2 marks)
I got -6x^-4+k can u explain what I did rong

When you integrate you add one to the power, not subtract one.

Reply 74

zcQ

For 6ii my working were completely correct it came out correct . I did the logs bit and got 17.2 because that was the actual answer. Would I lose marks for not rounding it down?
Thanks

Reply 75

Mr M

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Original post by mcavengers

For 7ii) I forgot to put the exact value so I put 1.23 (3sf) instead of 37/30. How many marks will I lose? :s

Drop 1 mark if you showed supporting working.

Reply 76

Mr M

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Original post by Namige

For 8 i) i said it crossed y axis at x= 0 therefore...

But i didn't state the coordinates specifically ie. In the format (x,y). Would i still get the mark ?

I don't think you will get any credit for that - sorry!

Reply 77

Zakee

Original post by Mr M

Unfortunately yes.

Dear Mr M,

For the geometric sequence question where n was less than or equal to 17.193..., I acheived that result with working out (which I believe was sufficient) and then I put n is less than or equal to (_<) 17 as it must be a whole number. However, I did not write n = 17, I wrote n _< 17 (less than or equal to). This seems to be quite a precarious mark because would I lose a mark, as technically N can limit up to 17, and it can't go past, but then I know that you could argue N could be any integer value below 17. Do you think I would lose a mark, and if so, only 1?

Reply 78

Mr M

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Original post by Whyllee

I got 59-62 marks do you think this will be an A? Everyone is saying it was easy, could you hazard a guess at the grade boundaries? :smile:

and also for 9ii) I got wrote (2x-3)(x+1) without the previous answer but then I wrote so x= -1/2 +2/3 or -1 will I lose a mark for having not written (2x+1)(2X-3)(X+1) ???

I don't guess grade boundaries. Think you will lose one for failing to fully factorise f(x).

Reply 79

Mr M

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Original post by dakenSoren

For 4b ii) evaluated it as lim _{n -> infinity}12/n = 0 therefore it is
(0) - (-12/a) = 3 therefore a = 4, as I forgot the square sign on the a and left it as a = 4 how many marks would I lose for this?