C3 Jan 2012 Edexcel - Post exam discussion - Solutions and paper in first post

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Reply 180

Wrathmeister

poor arsey having to deal with 9 pages of questions, c3 paper all over again:/

Reply 181

Arsey

Original post by CMPUNK

for q1 if i forgot to simplify how many marks would i lose

prob 1

Reply 182

Arsey

Original post by dude345

Will I lose a mark for leaving my answer as 28 minutes (to the nearest minute)

don't know but I doubt it as it would be very harsh

Reply 183

Mmrawrr

Will I lose a method mark for not showing how I got my second value for the very last question? I don't think I added 'pi - answer'. :redface:

Reply 184

theseeker

Apparently this was a hard paper compared to other years, so low boundaries? :-)

Reply 185

Arsey

Original post by annagoesbroom

If I put 2 extra solutions for question 5, am I likely to be marked down?

From a recent C3 MS

Note

If there are any EXTRA solutions inside the range 0 ≤ x < 2π,
then withhold the final accuracy mark if the candidate would
otherwise score all 5 marks. Also ignore EXTRA solutions
outside the range 0 ≤ x < 2π .

Reply 186

Arsey

Original post by battsa

For the normal to the curve, i got the correct x coordinate, the right dy/dx in terms of y but somehow worked the gradient out as -1/2 not -8. After that i made an equation using that gradient. How many marks will i have lost?

Got everything else right except the domain, i didn't know what was going on :P

hard to say, depends on what you did wrong, if everything else what perfect you prob lost 2 marks

Reply 187

Arsey

Original post by Mathssss

got a couple of questions,

on 1b how many marks would I lose for not simplifying to x^4?
on 8a how many marks for getting up to the part of dividing cosAcosB?
and lastly I got 5pi/12 and made an error when calculating the other angle and got 7pi/12, only 1 mark lost or 2?

1
1
2

Reply 188

Toshiya

For question 5 I ended up doing sinx = 1/3 instead of sin3x = 1/3 and got 19.5 and another answer...
Until the factorisation bit I had the rest of the working completely right, how many marks dyou reckon I'll have lost for that? Bearing in mind I did get sin3x = 2 and said it had no solutions.

I think I couldn't remember whether sin3x x sin3x = sin^2(3x) or whether it was sin3x x sinx. It was 50/50 which one I went for and I picked the wrong one... oops!

Reply 189

RedDevilThing

Lot's of people were complaining about Q5 and 8. They were big questions so lower grade boundaries are possible. Not that I'm particularly fussed, a quick scan over the mark scheme seems to show I aced that paper. :awesome:

Reply 190

Arsey

Original post by Mani94

Hey Arsey, for question 7d I re-wrote 2ln(x+1) as ln(x+1)^2, which gave me TWO solutions in the end. I got the one you got but I also got -e^4-1. Do you think I'll lose any marks for including the extra solution, and if so how many?

not sure, you might not lose any; at most 1 if you do. Depends what is specified in the MS, unless stated otherwise general rule is to ignore subsequent work / solutions once the correct one is given

Reply 191

Arsey

Original post by Ellis246

for question four i got it in the form y-y1=m(x-x1) and that was correct but made a stupid mistake expanding it, will i lose any marks?

prob not, for the reason above

Reply 192

holahola

Original post by theseeker

Apparently this was a hard paper compared to other years, so low boundaries? :-)

What do you think they will be ?

Reply 193

Arsey

Original post by CharrrrxD

Hi Arsey, or anyone else that can help!
Just a few questions
Firstly on the first question I got x + 2xln(3x) like you but simpfly this to x(1+2ln(3x) - is this likely to lose a mark for me?
Also on 6d, I recognised to use 1.90775 and 1.90785 but subbed them back into the iteration formula as x, and then xn+1 came out as 1.9078 to 4dp so I said that - am I likely to get any marks for this? Maybe 1 for recognising the interval?
Finally, on 7d, really stupid mistake, I wrote it as 2ln(x+1) +1 =1/7 and worked from there, ending up with e^3 -1 - opinions on marks out of 4 - would I likely get any method marks?

At worst I got 67 - the last 3 sessions 90 has been 70,68,69
What do people think of grade boundaries?

no
1
the last one is unfortunate, you prob will not get any

Reply 194

Arsey

Original post by StrawberryKoi

Don't worry, I think they said they do discourage the use of non-black pens and pencils because they tend to look a little faded on the scan but you are allowed to use a pencil for graphs :smile:

as long as they can see something is there, they can request the actual paper..

Reply 195

Arsey

Original post by Kenan and Kel

Arsey always uploads the solutions then runs off to bed grrr

jkjk we love you no homes

you are very lucky, I was barely awake.

Reply 196

Arsey

Original post by Dan12

two questions:
for the domain do you need xER as well as x>0

for question 6d you have to sub the values into (3+sin(1/2x)/2))-x
this sort of question came up in june 2006