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# OCR (not MEI) C1 - Wednesday 13th May 2015 watch

1. (Original post by ChoccyPhilly)
Oh, I knew that but I mean is he a teacher who just kindly posts the answers to us?
I assume so, not 100% sure to be honest.
2. would someone work out for me if i definitely got these questions right: 1, 2, 3i+ii, 4, 5, 7, 8, 9, 10i +ii what UMS and grade am i likely to get? can't remember the marks for all the questions!! thanks
3. (Original post by gabby07)
100% 40sq units
how many marks for not stating units
4. (Original post by gabby07)
I strongly believe though that this C1 was one of the hardest in the last 3-4 years of exams. You can expect the UMS boundaries to be lower.
I would disagree strongly, this seemed like a very average paper to me. The only difficult questions were finding k and the final area question.

Also it's better to assume you have a lower mark than you actually have so you don't get complacent!
5. (Original post by Dentist214)
Don't worry, I subtracted the 8 instead of plusing it and got a=11 and I couldn't find the other stationary point because of this mistake
I got same but i found the other stationary point as being 1/3 would i still get marks?
6. (Original post by Rr_rolo)
how many marks for not stating units
Full marks
OCR don't penalise unit errors/lack of units
7. (Original post by Rr_rolo)
how many marks for not stating units
I'm not entirely sure stating 'units squared' or not will matter at all. In January 2012, there was a similar question (10.iv) where in the mark scheme it just stated the value.
8. (Original post by Rr_rolo)
how many marks for not stating units
I have just looked through every single C1 mark scheme available on the OCR website (07-13) and of the 3 papers that have a similar question, 2 have no units stated in the mark scheme and 1 does. The 1 that has units does not mention anything about penalising students who fail to include units and at the start of the MS, it says - Wrong or missing units in an answer should not lead to the loss of a mark unless the scheme specifically indicates otherwise.
Based on this, I'd say no marks would be lost unless they decide to be especially harsh this year.
9. (Original post by chloe-jessica)
In the original post, click 'show spoiler'. The questions aren't in the right order as I can't remember the order (I have said people can correct me but nobody has) but the answers are there.
Sorry but I can't find it ???
10. (Original post by Charlieukharris)
Sorry but I can't find it ???
Go back to the first page and to the very first post I wrote here ("Okay so I couldn't find another thread.."). Click on the orange box that says 'show' next to the word spoiler, it should come up.
11. Omg what was answer for first transformation question?
12. (Original post by gabby07)
Hi can I just briefly turn attention to a C2 question I'm having a bit of trouble with (I know it ought to be easy, and I'm sure it is...!)

Can anyone help me out with this:

7x = 2x+1

Solve for x.

So far, I've got up to here:
log7x = log2x+1
xlog7 = (x+1)log2

I have no idea where to go from here! Normally you can just divide by logs to find the x solution and then act as necessary but the way to do this isn't appearing in my head! Thanks!!
Take logs of both sides as you did then divide through by both sides to get all x's on one and all logs on the other. Use fraction rules to get rid of the +1 with your x's (that you should get) then bang it into your calculator.
13. (Original post by Rr_rolo)
Omg what was answer for first transformation question?
Stretch [1]
Scale factor (1/3) [1]
(In either direction [x or y stated])
14. I got 40 and stated the area was 40, did you have to say sq units?
15. (3x-14)(x-2) therefore x = 14/3 or 2, then sub back in to find the y values! alternatively you could have used the quadratic formula to solve it
16. The question in the unofficial mark scheme as you've written differentiation? Does anyone have any idea?

Also, the k question was (I think) Q8, and the coordinate geometry was perhaps 4?
There was also a disguised quadratic with x = -8 and 27 or something like that.
The marks allocated in the order you have written your questions for the unofficlal mark scheme were I think:

1. 1) 4 + 4root3 [3]
2) can't really describe the graph, if you know what y=1/x looks like then reflect in either axis. [2]
Translation of 2 in x was -1/(x-2) [1]
The translation they wanted you to state was a stretch of 1/3 in either axis. [2]
3) 5^8 [1]
5^(-1/4) [2]
5^(9/2) [2]
x = -8 and 27 [5?]5) Line AB = ? [2]
Line was 6x-8y-29=0 [7]
5) differentiation? Can't remember the answer to this, was reasonably straight forward though if you expanded brackets.?
6) simultaneous equation - x=1, y=2 or x=14/3, y=-13/3 [5]
7) differentiate x^(-1/3)? Should get out -1/48 when you put x in. [4]
8) Draw the graph [4]
X < -1, X > 3/2 for y=0 [2]
k < - 25/8 [3]
9) a=13 [5]
Second derivative was positive therefore min point [2]?
X=1/3 [2]?
10) centre (5,-2) radius 5 [3]
Prove tangent [5]
Area of triangle = 40 [4]

I tried to amend it, but I could be completely wrong lol
17. (Original post by K-King121)
I got 40 and stated the area was 40, did you have to say sq units?
No, we think just 40 is enough (with correct working) for full marks on that question.
18. (Original post by Peppercrunch)
I found the paper easy, but apparently most people in my year said it was difficult?
it wasnt too difficult if u know c1 basics, they probably just needed to revise abit more :P it was a good paper
19. (Original post by Madhutty)
No, we think just 40 is enough (with correct working) for full marks on that question.
Correct working as in the correct coordinates and correct working for area of triangle?
20. The question about the stretch of -1/x

The answer is as follows:

Stretch
Scale factor 1/3
In EITHER direction

THIS GRAPH (http://puu.sh/hLU2t/a0228020ae.png) shows the pre-stretch graph, and the post-stretch graph.

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