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OCR C3 (not MEI) Official Thread - Tuesday 21st June 2016

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Reply 300
Avatar for oloym
oloym
Original post by SGHD26716
I would say you get all method marks but lose answer marks for not working out tan b correctly and therefore getting the wrong final answers so lose 3


Ah ok that makes sense, thanks!
Original post by oloym
Yeah I did its so annoying!! glad someone else is in the same boat


Literally dw like half the people in my year got 27😂 And it was such a silly mistake as well!! Ugh
I did something really stupid on Q4 :colonhash:

Found tanA and tan B correctly, went to sub into the tan(A-B) equation but wrote tan3 - tan(-3) or whatever instead of just 3 - -3... Dumb I know and really not sure how I didn't realise where it'd gone wrong. But just the first bit will get me 4 or so marks out of 8, right?
For the last part of the exponential question I got t=31.06 years for the mass to reach 50g, therefore rounded it to t=32 years because the mass wouldn't be 50g yet if I rounded it to t=31 years?! How many marks could this lose?
Honestly how low will the grade boundaries be? Personally I found it really difficult but I feel like most people found it fairly average..what do people reckon an A* would be?
62 A*

Original post by student2734
Honestly how low will the grade boundaries be? Personally I found it really difficult but I feel like most people found it fairly average..what do people reckon an A* would be?
Ok guys so for the tan question I got tan B and tan A correct, and got 1/13 as one of the answers but 0 as the other as i stupidly did -3+3 instead of -3--3 for the top bit so I didnt get the correct second solution. How many marks would I probably lose out of 8? I got tan B as 3 and tan A as 4 and -3.
Sooooo annoying on Question 3 I got tan^3theta=27 but put 9 instead of 3!!!! So annoyed!!!
Original post by Dom1997
I can't remember the exact question but I'll try to explain how I did it. You are told that P is a point on both curves and that x=2 so you know they intersect therefore you equate them then substitute in x=2 to have one equation with a's and b's. You are then told the gradient of the curves are equal at P so differentiate both curves sub in x=2 and equate the differentials to get a second equation with a's and b's. Then solve the equations with a's and b's simultaneously to get a=6 b=5. I hope this helps?


I did exactly that method but didn't get those answers! Must have made a stupid mistake somewhere along, so annoying! Thank you though!
Reply 309
Avatar for S.G.
S.G.
22
Original post by zintanax
Ok guys so for the tan question I got tan B and tan A correct, and got 1/13 as one of the answers but 0 as the other as i stupidly did -3+3 instead of -3--3 for the top bit so I didnt get the correct second solution. How many marks would I probably lose out of 8? I got tan B as 3 and tan A as 4 and -3.

You will only lose A1 for answer mark
Reply 310
Avatar for S.G.
S.G.
22
If my answer is correct but working is not fully clear is there a chance I lose marks.

So for the tan(a-b) question when working out tan b, In got a degree 5 polynomial. I then wrote down the value of tan b. My answers are right, but would I lose marks for not showing every step in my working.
Reply 311
Avatar for RmAthS
RmAthS
1
Original post by Boldon25
For the last part of the exponential question I got t=31.06 years for the mass to reach 50g, therefore rounded it to t=32 years because the mass wouldn't be 50g yet if I rounded it to t=31 years?! How many marks could this lose?


I did the same thing and I'm not sure if it is correct or not. If it is incorrect though you'd only lose 1 mark
Reply 312
Avatar for RmAthS
RmAthS
1
Original post by SGHD26716
If my answer is correct but working is not fully clear is there a chance I lose marks.

So for the tan(a-b) question when working out tan b, In got a degree 5 polynomial. I then wrote down the value of tan b. My answers are right, but would I lose marks for not showing every step in my working.


I don't see why you'd lose any marks if your final answer was correct and there was at least a few lines of working
I don't remember any questions involving volumes of revolution or Simpson's rule. Was there any? Just to make sure I have attempted all questions.
A* grade boundaries, what we thinking?
Original post by tangotangopapa2
I don't remember any questions involving volumes of revolution or Simpson's rule. Was there any? Just to make sure I have attempted all questions.


And no rates of change either. That's time spent learning 1/4 of the syllabus wasted.
Reply 316
Avatar for Turbzz
Turbzz
What did Q7iii ask, just to find new equations?
Original post by micycle
And no rates of change either. That's time spent learning 1/4 of the syllabus wasted.


Volume of revolution and rates of change can and have come up in C4, so it's not a waste of time learning it.
Original post by Mrrexxxx
A* grade boundaries, what we thinking?


People are guessing ~62 +/- 2. But the lowest ever was 58 in June 2011 so who knows? Hope we get lucky anyways.
Guys for Question 4, I can't seem to find B in the second equation it's given. Can anyone help me with this please? Many thanks.

The second equation that is given is: sinBsec^2B = 27cosBcosec^2B
(edited 7 years ago)

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