AQA Core 4 Exam Discussion 14/06/2012 !Poll, paper and unofficial MS (first post)!

Did any of you guys see question 12 on the back? It was Soooo difficult. What did you guys get?

This was posted from The Student Room's Android App on my GT-N7000

If so, I'd be more worried by the fact that you would then have missed out on a question 9, question 10, and question 11..

(edited 11 years ago)

Reply 941

f1mad

13

Original post by Rennit

I'v looked at numerous exam threads and they've ALWAYS said there will be low marks; there hasn't really been much change.

I'd say that TSR is actually below average.

Loads of people say they found it really hard, it wasn't much different from any of the other papers!

You're looking at it rather blindly. The recent papers weren't very difficult (see June 2011) yet, they had ridiculously low grade boundaries.

Why? Because even the best and most able candidates falter under pressure.

Reply 942

Oromis263

2

Original post by Oromis263

Home.

Question 7.

a)

Unparseable latex formula:

l_1 = l_2 [br]\[br][br] \begin{bmatrix} 2\lambda \\ -2 \\ q - \lambda \end{bmatrix} = \begin{bmatrix} 8 + 2\mu \\ 3 + 5\mu \\ 5 + 4\mu \end{bmatrix}[br][br]\[br] [br] [br][br]so\ 2\lambda = 8+2\mu[br]\[br]-2 = 3 + 5\mu[br]\[br]q-\lambda = 5 + 4\mu[br]\[br]\Rightarrow \mu = -1 \Rightarrow \lambda = 3[br]\[br]q = 3 + 5 -4 = 4[br]\[br]P (6, -2, 1)

b)

Unparseable latex formula:

\begin{bmatrix} 2 \\ 0 \\ -1\end{bmatrix} \bullet \begin{bmatrix} 2 \\ 5 \\ 4 \end{bmatrix}[br]\[br]\Rightarrow 2(2) + 0(5) -1(4) = 0 \Rightarrow cos\theta = 0, \theta = 90\ \therefore\ perpendicular

I think I'll do the rest of this one by hand and upload a picture >.<

Thus coordinates of B were

(4\dfrac{2}{3}, -5\dfrac{1}{3}, -1\dfrac{2}{3})\ and\ (7\dfrac{1}{3}, 1\dfrac{1}{3}, 3\dfrac{2}{3})

Updated.

Reply 943

f1mad

13

Original post by Oromis263

Updated.

Mixed fractions, ewww.

:tongue:

Reply 944

Rennit

Original post by f1mad

You're looking at it rather blindly. The recent papers weren't very difficult (see June 2011) yet, they had ridiculously low grade boundaries.

Why? Because even the best and most able candidates falter under pressure.

I dont? :\

Reply 945

Oromis263

2

And finally!
Question 8.

a)

\dfrac{dh}{dt} \propto 2-h \Rightarrow \dfrac{dh}{dt} = k(2-h)

bi) This is a lot of work, I used integration by parts, but integration by substitution was another viable method (or any other way that got you to the answer really!) :smile:

Final equation

t = (3x+1)(2x-1)^{\dfrac{3}{2}} - 4

bii) Sub 2 in to above formula.

t = 7 \times 3^{\frac{3}{2}} -4 = 32.4

And that is it! :smile:

Reply 946

VQG

11

Original post by SomeoneIveNeverMet

I think, outside of exam conditions, the papers do seem rather easy. But I guess when you're in the there it's more a panic, and so people make silly mistakes.

I think the grade boundaries are lower when the examiners have created more chances for people to get caught by silly mistakes.

But I'm the same as you; A-level A grade, fine, whether it's an A* or not, that's another matter.

This is what happened to me.. I completely broke down under pressure today. First time that's ever happened to me. I only needed 34 UMS for an A and I'm not sure if I've got that. I completely broke down in the exam for some reason, the questions looked much harder than when I looked at the paper at home. Maybe it's because I knew it was my last shot no retakes - but even then I had my last Chemistry exam yesterday and I felt okay in that. I went into the exam thinking no pressure I'll get 34 marks, but as soon as I sat down I panicked.

Reply 947

jammysmt

5

I did the full equation of the normal line in a question (3 or 4 I think). I said the gradient (1/3) at one point but do you think they'll mark me down for the equation? ( damn we reading the question wrong!)

Also I used integration by parts and came up with a different equation but the same constant and value of t. Think I'll still get full marks or any marks at all for that? Cheers :smile:

This was posted from The Student Room's iPhone/iPad App

Reply 948

Oromis263

2

Original post by f1mad

Mixed fractions, ewww.

:tongue:

I wrote both as my answer, however I agree. It was just I did a paper at some point that gave it in mixed fractions, and nothing else. I didn't want any silly examiner missing the fact I'd got it correct :wink:

(also made sure I noted which two were the same as each other etc, I am so paranoid the marker would be just like, "pssht, 4 solutions? WRONG!") :P

Reply 949

Zoe_mj

Original post by Oromis263

Updated.

I found BP instead of PB which gave me lots of negatives in brackets which simplified to the same expression only a negative x-term, 9x^2 - 18x + 5, so my factors were (3x-5)(3x-1) so I got positive values of x = 1/3 and 5/3.
Which gave me different coordinates :frown:

How many marks do you think I'll lose?

Reply 950

Rahul.S

14

Original post by f1mad

As I said, it comes down to how the majority found it.

Nobody I know in my college found it particularly nice (apart from myself :tongue:

).

nice to hear bro....ADD ME ON SKYPE :biggrin:

i made an account brah...GRIMESTARR :colone:

Reply 951

In One Ear

18

Original post by f1mad

dx/dt= k(2-h).

dh/dt=k(2-h). They might condone that though. Maybe not though, because then for the equation to make sense you should have written dx/dt=k(2-x).

Overall relieved. Think i can pretty much bet on the A* now for core maths. All went perfectly besides the vector question where i (predictably) made some arithmetic slips and got ap^2=60 instead of 20 which obviously led to some pretty groovy coordinates for the two positions of B.

The paper wasn't really that bad though. The only hard bits was the 3 mark rearrangement for the parametric equation ( at least i managed to run around in circles a bit), POSSIBLY the 8 mark implicit differentiation question ( it wasn't hard at all- but it was long and unguided and they havn't asked questions on this topic really much recently) and then maybe the 8 marker in the final question (but it really was just by parts or an easy substitution (personally i substituted).

That said, the grade boundaries aren't really determined by the intrinsic difficulty of a paper, but more by how everyone performed. Given a lot of people seem to have had great difficulty/time issues we can probably expect low boundaries.

I would hazard that the boundaries will be between those of June 011 and Jan 012, as in about 55 for an A, 62 for an A*. I don't really know why junes boundaries were so crazily low though, i found jan 012 harder personally.

Anyway, good luck all, stop stressing we can't do anything about how it went and just hope that low boundaries give you the UMS you need/focus on whatever maths exams you have left (if you have any) and make up for a poor performance in these!

Reply 952

Neimad

1

Original post by Oromis263

And finally!
Question 8.

a)

\dfrac{dh}{dt} \propto 2-h \Rightarrow \dfrac{dh}{dt} = k(2-h)

Isn't it dh/dt=k/(2-h) ??

The rate of increase of depth is proportional to the change in difference between maximum depth and current depth

As depth increases, the distance between the water level and the rim (2-h) decreases - therefore rate of increase of depth would be inversely proportional to the difference.

(edited 11 years ago)

Reply 953

mojopin1

Did anyone else find there wasn't really enough time? I got to the last question with about 15 minutes to go thinking it would be alright because I usually ace differential equations, but that one completely threw me and I know i've lost 8/9 marks. It's annoying because i'm pleased with how the rest of the paper went. I was sat for about 5 minutes trying to figure out how to separate the variables.. I actually thought it could be integration by substitution but I wouldn't have had the time anyway. June 2011 was piss compared to this one.

Reply 954

In One Ear

18

Original post by Oromis263

And finally!
Question 8.

a)

\dfrac{dh}{dt} \propto 2-h \Rightarrow \dfrac{dh}{dt} = k(2-h)

bi) This is a lot of work, I used integration by parts, but integration by substitution was another viable method (or any other way that got you to the answer really!) :smile:

Final equation

t = (3x+1)(2x-1)^{\dfrac{3}{2}} - 4

bii) Sub 2 in to above formula.

t = 7 \times 3^{\frac{3}{2}} -4 = 32.4

And that is it! :smile:

Would just like to offer that if you did this question by substitution, the form you get to is t=2/3(2x-1)^(5/2)+2/5(2x-1)^(3/2) -4 EDIT: ACTUALLY t=3/2(2x-1)^(5/2)+5/2(2x-1)^(3-2) -4
which is the same thing (though i don't think anyone will have bothered trying to condense this down).

(edited 11 years ago)

Reply 955

ANTI-GADDAFI

7

I ran out of time. Other than that I would have scored 90+

This was posted from The Student Room's iPhone/iPad App

Reply 956

Oromis263

2

Original post by Zoe_mj

I found BP instead of PB which gave me lots of negatives in brackets which simplified to the same expression only a negative x-term, 9x^2 - 18x + 5, so my factors were (3x-5)(3x-1) so I got positive values of x = 1/3 and 5/3.
Which gave me different coordinates :frown:

How many marks do you think I'll lose?

I honestly couldn't say. It was out of 6, so you perhaps picked up a couple for your methods, but I don't think you'll get any accuracy marks? That being said, I'm not an A-level exam marker, I'm just a mere student. :smile:

Reply 957

Zoe_mj

Original post by Oromis263

I honestly couldn't say. It was out of 6, so you perhaps picked up a couple for your methods, but I don't think you'll get any accuracy marks? That being said, I'm not an A-level exam marker, I'm just a mere student. :smile:

Hopefully

Thanks for putting all the answers on :smile:

Reply 958

myoaontw

anyone else heard that grade boundaries are usually lower in summer exams than januarys cause of something to do with further maths candidates taking them in january?.. or just me being optimistic

Reply 959

mojopin1

I hate the period of time after exams when I start analysing everything I did (or didn't do). I got the correct values of u for the vector question but now i'm fretting if I calculated the coordinates correctly without any slips, ffs.

AQA Core 4 Exam Discussion 14/06/2012 !Poll, paper and unofficial MS (first post)!

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