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

joebloggs1994

on the 8 mark implicit differentiation question, i got the gradient right and put down that it equals 0, and then i put 18X-6Y=0 and re-wrote the initial equation (implying they were similataneous) then kind of trial and errored my way to the right co-ordinates (i know, stupid)... will i still got all 8 marks since it didnt specify how you had to get to the right co-ordinates?

Reply 1181

Oromis263

2

Original post by mojopin1

Is this true for most of the questions? If you have the correct answer with some working you get full marks?

Most probably, but I'm not sure. It's often best to be safe and put it all down, but I wouldn't worry about it now :smile:

If you got the right answer, you got the right answer. :smile:

Reply 1182

OnimushaGTA

8

Original post by sshah210

Used the unofficial MS and paper to work out i got about 46 Raw marks. Really need 70 UMS for an A. Just hope the boundaries are around this, anyone got ideas what the boundaries will be?

46 is about 61percent
However in June, that would actually give you 70UMS!

But here's to hoping...!

Reply 1183

In One Ear

18

Original post by joebloggs1994

on the 8 mark implicit differentiation question, i got the gradient right and put down that it equals 0, and then i put 18X-6Y=0 and re-wrote the initial equation (implying they were similataneous) then kind of trial and errored my way to the right co-ordinates (i know, stupid)... will i still got all 8 marks since it didnt specify how you had to get to the right co-ordinates?

Well for starters the two equations were in effect "simultaneous" given that that really means that x and y must satisfy both equations simultaneously (which they did have to). Its just that the expected way to solve the question (presumably) was to rearrange for one variable and sub back in because trying to seperate out the initial equation and find some multiple to be able to subtract/add the equations to cancel a variable would have been a nightmare.

With respect to having used trial and error- they would be very within rights to take away all the following method marks because trial and error has diminishing feasibilty as equations grow in complexity and you are supposed to be showing a quick and logical method of producing a solution.

They also sometimes have A1 dM1 which reads accuracy mark 1 dependant on method mark 1 so its not even certain that you'd get all the accuracy marks- in short its hard to know exactly what you'll get but i'd count on losing at least a couple of marks i'm afraid.

Reply 1184

freakymonkey

4

Original post by mojopin1

Is this true for most of the questions? If you have the correct answer with some working you get full marks?

It's true for all the questions. As long as the answer you come to could have been achieved using a permitted calculator, you get full credit for a correct answer. There are a few lines of text on page 2 or 3 of each mark scheme to this effect. This does not apply to show that questions, where all of the marks are method marks.

The downside to this is if you are wrong, by however small an amount, you will lose all the marks associated with the method you did not show, as well as the answer marks.

Reply 1185

Kalv

Original post by OnimushaGTA

Same boat as you, this was the exam that mattered the most!! I'm so annoyed!!

Really praying for low grade boundaries!!!

Same, hopefully I can still get a B overall if I can get an A in S2 but that's unlikely as its so hard haha.
So annoying though all that revision and I went and completely messed up the exam :mad:

Reply 1186

1platinum

10

For question 8a I am so annoyed because at first I put dh/dt = k(2-h), but then I saw that it wanted to include t and ended up changing it to dh/dt = kt(2-h). So does anyone know how many marks I will lose for that. Also for question 1b, if you got the values of p, q and r wrong will you get any follow through marks for the integration? Thanks to anyone who can help. :smile:

Reply 1187

joebloggs1994

Original post by In One Ear

Well for starters the two equations were in effect "simultaneous" given that that really means that x and y must satisfy both equations simultaneously (which they did have to). Its just that the expected way to solve the question (presumably) was to rearrange for one variable and sub back in because trying to seperate out the initial equation and find some multiple to be able to subtract/add the equations to cancel a variable would have been a nightmare.

With respect to having used trial and error- they would be very within rights to take away all the following method marks because trial and error has diminishing feasibilty as equations grow in complexity and you are supposed to be showing a quick and logical method of producing a solution.

They also sometimes have A1 dM1 which reads accuracy mark 1 dependant on method mark 1 so its not even certain that you'd get all the accuracy marks- in short its hard to know exactly what you'll get but i'd count on losing at least a couple of marks i'm afraid.

I didn't actually put that i was using trial and error, ive just kind of jumped from dy/dx=0 to the co-ordinates.

Reply 1188

Cath-ay

OP

Original post by 1platinum

For question 8a I am so annoyed because at first I put dh/dt = k(2-h), but then I saw that it wanted to include t and ended up changing it to dh/dt = kt(2-h). So does anyone know how many marks I will lose for that. Also for question 1b, if you got the values of p, q and r wrong will you get any follow through marks for the integration? Thanks to anyone who can help. :smile:

I'm no expert but I would reckon 2 marks for 8a (1 for dh/dt and the other for 2-h possibly?)
For 1bii), you might have gotten 1 or 2 method marks depending on whether you fell for their silly trick. :/

(edited 11 years ago)

Reply 1189

rachaelizabeth

4

I'm so disappointed with this exam - I truly believed that I was capable of getting an A* in Maths this year but now it's just impossible. I've worked it out and I've only got about 48 or 49 out of 75, which under standard grade boundaries is a low-mid 'C'. I'm genuinely distraught as I was getting at least 80% of the raw marks on most of the past papers, often hitting 90%.

*Closes eyes for 2 months and prays for low grade boundaries...*

Reply 1190

sunnybacon

12

Original post by rachaelizabeth

I'm so disappointed with this exam - I truly believed that I was capable of getting an A* in Maths this year but now it's just impossible. I've worked it out and I've only got about 48 or 49 out of 75, which under standard grade boundaries is a low-mid 'C'. I'm genuinely distraught as I was getting at least 80% of the raw marks on most of the past papers, often hitting 90%.

*Closes eyes for 2 months and prays for low grade boundaries...*

I reckon the boundaries will be fairly low...
I mean, last year's June paper was just 58 for A*, and I think this paper was harder than that one - maybe not in terms of its actual question content, but there were a lot more places to potentially make silly mistakes on this paper. And I found the timing a lot harder, I know it was under pressure but even so, it just seemed a LOT tighter than past papers.
So basically I think both those factors will bring the boundaries down :tongue:

(edited 11 years ago)

Reply 1191

1platinum

10

Original post by Cath-ay

I'm no expert but I would reckon 2 marks for 8a (1 for dh/dt and the other for 2-h possibly?)
For 1bii), you might have gotten 1 or 2 method marks depending on whether you fell for their silly trick. :/

Thanks for the reply. I really hope so for question 8a. Damn, what was their silly trick on 1bii?

Reply 1192

croasdaj

The grade boundaries for core 4 in June are lower than in January, purely because 90% of students sit core 4 in June. The only people who sit it in January are people who do further maths or people re-sitting from the year before! I would expect the grade boundaries to be similar to June 2011, everyone I spoke to found it pretty damn hard! I think I've dropped a couple of marks on binomial expansion and cartesian equation, hit and miss whether I get an A* :smile:

People will have done better than expected!

Reply 1193

OnimushaGTA

8

Original post by croasdaj

The grade boundaries for core 4 in June are lower than in January, purely because 90% of students sit core 4 in June. The only people who sit it in January are people who do further maths or people re-sitting from the year before! I would expect the grade boundaries to be similar to June 2011, everyone I spoke to found it pretty damn hard! I think I've dropped a couple of marks on binomial expansion and cartesian equation, hit and miss whether I get an A* :smile:

People will have done better than expected!

If you've only dropped a couple of marks, it won't be as low as it was last June sadly. If students are closer to full marks, then grade boundaries wont be as low; and judging by the answers..etc on here, some people have done better than they thought :s-smilie:

Not disagreeing with you, I really want it to be low!

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

Reply 1194

Harantony

10

Original post by rachaelizabeth

I'm so disappointed with this exam - I truly believed that I was capable of getting an A* in Maths this year but now it's just impossible. I've worked it out and I've only got about 48 or 49 out of 75, which under standard grade boundaries is a low-mid 'C'. I'm genuinely distraught as I was getting at least 80% of the raw marks on most of the past papers, often hitting 90%.

*Closes eyes for 2 months and prays for low grade boundaries...*

Ditto!

----------
Harantony
Posted on my iPod :smile:

Reply 1195

Cath-ay

OP

Original post by 1platinum

Thanks for the reply. I really hope so for question 8a. Damn, what was their silly trick on 1bii?

Welcome

you had to divide your r value by (2x+1) then intergrate to get 0.5r ln(2x+1). Some people over looked this like I did -.- Don't know about you :/

Reply 1196

Quexx

Original post by wendy31193

Huh? Can somebody please explain how to do question 8, the differential equation, because i keep getting the answer to be 10x(2x-l)^1.5 + 4(2x-1)^2.5 -6

8a

dh/dt = k(2-h)

8bi
dx/dt = 1/(15x(2x-1)^0.5))

[Separate the variables, and integrate both sides]

∫(15x(2x-1)^0.5)dx = ∫(1)dt

[The right side integrates to t + c, the left side need integration by parts]

∫(u dv/dx) dx = uv - ∫(v du/dx) dx [LHS only]

[u=15x du/dx=15, dv/dx=(2x-1)^0.5 v=1/3(2x-1)^1.5

∫(15x(2x-1)^0.5))dx

= (15x)(1/3(2x-1)^1.5) - ∫(15)(1/3(2x-1)^1.5))dx

= 5x((2x-1)^1.5) - 5∫((2x-1)^1.5)dx

= 5x((2x-1)^1.5) - 5[1/5((2x-1)^2.5)]

= 5x((2x-1)^1.5) - ((2x-1)^2.5)

[Take (2x-1)^1.5 out as a factor]

= ((2x-1)^1.5)[5x - (2x-1)]

= ((2x-1)^1.5)(3x+1) [LHS]

[Overall integrated equation]

t + c = ((2x-1)^1.5)(3x+1)

[Find c]

c = ((2x-1)^1.5)(3x+1) [where]

c = 4

t = ((2x-1)^1.5)(3x+1) - 4

8bii

[Find]

t = ((3)^1.5)(7) - 4

t = 32.4 minutes

Reply 1197

1platinum

10

Original post by Cath-ay

Welcome

you had to divide your r value by (2x+1) then intergrate to get 0.5r ln(2x+1). Some people over looked this like I did -.- Don't know about you :/

Think I have messed up that too. May have only got 49/75. :frown:

Reply 1198

Cath-ay

OP

Original post by 1platinum

Think I have messed up that too. May have only got 49/75. :frown:

Damnn

hate what exam boards put us through. Is that worst case scenario? Could still be a B? :/
Besides, nothing is for sure yet because it depends on the actual mark scheme. But I do hope you did better than you think you did :smile:

Reply 1199

1platinum

10

Original post by Cath-ay

Damnn

hate what exam boards put us through. Is that worst case scenario? Could still be a B? :/
Besides, nothing is for sure yet because it depends on the actual mark scheme. But I do hope you did better than you think you did :smile:

Hope so, thanks for the support! :smile:

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

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