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

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Original post by roselle.orleans
Oh, wow. Thats better than I expected. Thank you so much for the help. I've been beating myself up for the stupid mistakes I've done. Now, I kinda feel better. Thanks for the mark scheme! :smile: You're the best! :biggrin:


Ok you're welcome.
Original post by Big-Daddy
1) For 6ii), I ended up with N <= 17 (not N=17). This doesn't lose any marks does it? After all the inequality was 1.3^N <= (something, forgotten what), not 1.3^N = (that something).

2) For 5ii), I wasn't sure if perimeter included the line BD as that wasn't on the surface of the shape, so I just wrote down both possible answers specifying that perimeter = 34.0 but if the question means only to count the lines on the surface then perimeter = (34.0 - BD, forgotten the value of BD now). Would I lose any marks?


6ii) drop 1 - the question says N is the greatest integer value that satisfies the inequality

5ii) It's not multiple guess - you will lose 1 mark - only one region BDC is marked on the diagram
For question 8 ii, it took me ages to figure out, and I did lots of working resulting in a very messy answer booklet. I used the extra paper booklet and there were loads of crossing. (Literally used two sides of working with crossing out etc until I got the final answer) I did eventually get the correct answer, but is there a risk of losing marks for bad layout?
Original post by Mr M
5ii) It's not multiple guess - you will lose 1 mark - only one region BDC is marked on the diagram


Even though I explicitly stated the perimeter = 34.0, and then wrote in brackets that, if they were asking for something different, it would be =(this different answer) instead?
Original post by Big-Daddy
Even though I explicitly stated the perimeter = 34.0, and then wrote in brackets that, if they were asking for something different, it would be =(this different answer) instead?


Sorry - it's wrong. You demonstrated that you didn't understand the question which was unambiguous.
Reply 145
Avatar for James_01
James_01
Mr M

Hi (again)


For 6)i) i misread the summation formula for an arithmetic question and wrote down a instead of 2a and so got the wrong answer although all other values were subbed in correctly, how many would i drop?

For the very last question i got 2/3pi ,pi, discluded cos^-1 3/2 but instead of doing 2 pi -2/3 pi i did pi + 2/3 pi getting 5/3 pi not 4/3 pi and i wanted to know if i'd drop 1 or 2?

thanks
Original post by eggfriedrice
For question 8 ii, it took me ages to figure out, and I did lots of working resulting in a very messy answer booklet. I used the extra paper booklet and there were loads of crossing. (Literally used two sides of working with crossing out etc until I got the final answer) I did eventually get the correct answer, but is there a risk of losing marks for bad layout?


No. The examiner will curse but you will get all the marks if the answer is there somewhere.
Original post by Mr M
No. The examiner will curse but you will get all the marks if the answer is there somewhere.



Haha, sorry Mr. Examiner! But that's a relief, thanks (:
Original post by James_01
Mr M

Hi (again)


For 6)i) i misread the summation formula for an arithmetic question and wrote down a instead of 2a and so got the wrong answer although all other values were subbed in correctly, how many would i drop?

For the very last question i got 2/3pi ,pi, discluded cos^-1 3/2 but instead of doing 2 pi -2/3 pi i did pi + 2/3 pi getting 5/3 pi not 4/3 pi and i wanted to know if i'd drop 1 or 2?

thanks


6i) drop at least 2 (misreading the formula book does not count as a misread)

last question drop 1
Would I receive marks if for the intercepts I just put 1 and 4 instead of (0,1) and (1,4)?
Reply 150
Avatar for ZachM
ZachM
What was question 4ii)


Posted from TSR Mobile
Hi Mr M,

For the logs question 8ii, I wrote:
a^x=4b^x
b=2/a
xlog2a=xlog2(4(2/a))
xlog2a=xlog2(4)+xlog2(2)+xlog2a
2xlog2a+(1)x=(2)x
x(2log2a+1)=2x
Then I wrote the answer. Would I get any marks?
Thanks
Original post by Matternot
Would I receive marks if for the intercepts I just put 1 and 4 instead of (0,1) and (1,4)?


I don't think so.
Reply 153
Avatar for Dugald
Dugald
On the sinx=3cosx I did
1=3cosx/sinx=3tanx
tanx=1/3 and solved tanx to 1/3

How many marks will I lose?
Original post by Ellie_Rosa
Hi Mr M,

For the logs question 8ii, I wrote:
a^x=4b^x
b=2/a
xlog2a=xlog2(4(2/a))
xlog2a=xlog2(4)+xlog2(2)+xlog2a
2xlog2a+(1)x=(2)x
x(2log2a+1)=2x
Then I wrote the answer. Would I get any marks?
Thanks


2 marks I think.
Mr M,

For the perimeter of the region question I got the side BD to be 7.51cm using BD^2 = 7^2 + 16^2 - 2(7x16) x cos(0.8) which gave me 56.433... which hence gave me 7.51, I got the arc length and the side of 9cm correct though. How many marks would I lose?
Original post by Dugald
On the sinx=3cosx I did
1=3cosx/sinx=3tanx
tanx=1/3 and solved tanx to 1/3

How many marks will I lose?


You'll get one mark if you are lucky.
Original post by Mr M
2 marks I think.


Thank you!
Original post by AlmightyPhil
Mr M,

For the perimeter of the region question I got the side BD to be 7.51cm using BD^2 = 7^2 + 16^2 - 2(7x16) x cos(0.8) which gave me 56.433... which hence gave me 7.51, I got the arc length and the side of 9cm correct though. How many marks would I lose?


Well the working is correct even if your use of the calculator leaves a lot to be desired. Drop 1 mark.
Original post by ZachM
What was question 4ii)


Posted from TSR Mobile


Given that ∫a∞24x−3 dx=3\int_a^{\infty} 24x^{-3} \, dx=3 find the value of the positive constant a.

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