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# OCR MEI AS Mathematics Core 1 13/05/2013 Watch

1. (Original post by krishkmistry)
I get that - but what do you all think it will be?

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80% = 57-58

but I think that question 13 (iii) was awkward for a lot of people, except for the few that spotted the correct way to do it.
i've heard from a few of the higher graders in my year that thye found this a big hard at points so i'm going to say 55-53.
2. (Original post by Deceived)
For the very last question, did people get k=0 or k=4?

Thanks
Both Checked a few ways and these are the only 2 numbers that work
3. (Original post by PreppyNinja)
Hope so. Was the Y-value 2root11?
2-rt11 and 2+rt11 because the roots can be positive and negative, and the circle crosses twice
4. (Original post by Deceived)
I think the equation went:

V=1/3*pi*r2*(a+b)
3V=pi*r2*(a+b)
3V/pi=r2*(a+b)
3V/(pi*(a+b))=r2
r=Pos/Neg (3V/(pi*(a+b))1/2

Hope that helps.
Think the root had to be positive as it said r>0
5. You know if the grade boundaries aren't low, I think I managed a C/B which is bad! :/

Too many silly mistakes
6. (Original post by jojo19apr)
Think the root had to be positive as it said r>0
Yeah I forgot the question. That was just off the top of my head. Hopefully, in the exam I didn't put (pos/neg). Can't remember.
7. (Original post by Soho32)
for the evaluate 0.2^-2 was it okay to leave the answer as a fraction? i.e 1/0.04?
Not sure as it said simplify, and you haven't fully simplified it. I found it easier to look at it as (1/5)^-2, then you have 5^2 and can see easier that it is actually 25.
8. (Original post by jojo19apr)
Not sure as it said simplify, and you haven't fully simplified it. I found it easier to look at it as (1/5)^-2, then you have 5^2 and can see easier that it is actually 25.
omg cant believe i didnt see that

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9. (Original post by TheNote)

(1/5)^-2

(5/1)^2

5^2 = 25

since 1/0.04 = 25 then you should be okay even if youe method is a bit of a weird way round it.
Do you think a triple decker fraction is ok - I put 1/(1/25) ?

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10. (Original post by krishkmistry)
Do you think a triple decker fraction is ok - I put 1/(1/25) ?

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yeah because they are equivilent:
→ 1/1/25 = (1*25)/1
11. Guys what about the question 4 or 5
It was something like 10+7sqrt5 + 38 over 1-2sqrt5
12. Does anyone know of an unofficial mark scheme available online?
13. (Original post by Sonicsuper)
Guys what about the question 4 or 5
It was something like 10+7sqrt5 + 38 over 1-2sqrt5
Yeah:

10+7√5+38/(1-2√5)

=10+7√5+(38)(1+2√5)/(1-2√5)(1+2√5)

=10+7√5+(38+76√5)/(1-2√5+2√5-4√25)

=10+7√5+(38+76√5)/(-19)

=10+7√5-2-4√5

=8+3√5

That's what I got. Hope this helps.
14. (Original post by Deceived)
Yeah:

10+7√5+38/(1-2√5)

=10+7√5+(38)(1+2√5)/(1-2√5)(1+2√5)

=10+7√5+(38+76√5)/(1-2√5+2√5-4√25)

=10+7√5+(38+76√5)/(-19)

=10+7√5-2-4√5

=8+3√5

That's what I got. Hope this helps.
I got 12 + 11root5....
15. (Original post by Sonicsuper)
I got 12 + 11root5....
16. (Original post by Deceived)
17. (Original post by Sonicsuper)
No problem. I made an egregious error in the exam. I'm so fortunate I checked my answers.
18. Reckon 56 for an A
19. Is there an unofficial mark scheme available anywhere by any chance?
20. (Original post by Sonicsuper)
I got 12 + 11root5....
All you did wrong was add (2 + 4root5) instead of taking away. Otherwise you would have got the right answer

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