STEP 2016 Solutions

no, in terms of m, M, and a, where a was the answer to the first part of the question

Oh dear. I deserve one sharp whack for being an idiot and running into the question without reading it. I left it in terms of m, M and R. It was just one simple absolutely basic substitution for heaven's sake.

How much do you think they'll dock for it?

Reply 161

fa991

3

Can someone estimate my mark please 😞:

1: Did the sketch and found both intersections but didn't get very far on the first part, found gradients and equations of tangent (one of which I think was correct)

2: Not much, showed a+b+c was a factor then found x=1 on the cubic

3: showed that f'(x) was fn-1 and that a was negative

Differential eqn: verified both equations and proved the result for z, then differentiated v but didn't get very far

Integration: did first three parts correctly then next to nothing of the last part

Other integration: drew a vague sketch with some trapezii, couldn't prove the result. Got the three approximations and showed the error.

Q13: Proved all three results but only had continuity corrections on the first one

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Reply 162

Zacken

OP

22

Original post by MathHysteria

Seriously, has nobody got a copy of the paper? I want to get my teeth into it over the weekend!

See the OP. :smile:

Reply 163

liamm691

can someone see if I got enough for a 1 😁

1 - got equation of tangents and found x, didn't get y or show it intersected on the line, but went on to do the sketch of the two curves with the intersection

3 - did first two parts and showed fn'(a) fn'(b) < 0 but got stuck at the sketches

6 - got the first two parts
7 - full, lovely question

9 - did part i, then got ii in terms of (M m a and u) not just (M m and a)
11 - full but got the inequality the wrong way round, so kinda fudged it, hopefully in the right place

Reply 164

Zacken

OP

22

Original post by liamm691

can someone see if I got enough for a 1 😁

Definitely. I envy you. :tongue:

Reply 165

username1162972

18

Original post by shamika

Nope, it's fine, I wish you were around this morning so I could avoid tying myself in knots. (I still stand by my estimates, but the obvious caveats apply. If I get some time I will try a few questions over the weekend to refine my view, but it's unlikely I'll have the time)

Your S boundary is too high since.
When in 2014 it was 95/74
In 2013 it was 100/79

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Reply 166

mathsman22

1

Anyone have a solution for 9?

Solution to 11

Original post by YonRamires

9: complete, but in the last part I calculated the path of the bullet relative to the table (so b+c instead of b), so I got the value of b wrong

Are you sure that is wrong? That's how I interpreted the question.
It says "The bullet travels a distance b inside the block before coming to rest relative to the block."
I took that to mean "In the time from when the bullet enters the block to when it comes to rest relative to the block, it travels an absolute distance of b."
I did wonder at the time, because I can see both interpretations, but I took that one.

Reply 169

krishdesai7

3

Here's Q7

file-page1.jpg280.3KB

file-page2.jpg341.0KB

file-page3.jpg388.5KB

file-page4.jpg321.2KB

New Doc 3.compressed.pdf664.5KB

file-page5.jpg397.6KB

file-page6.jpg242.4KB

Reply 170

shamika

16

Original post by physicsmaths

Your S boundary is too high since.
When in 2014 it was 95/74
In 2013 it was 100/79

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They're not set as a multiple of each other (or requiring 21 marks between them). I'm saying the best candidates will find it easy but the 1/2 boundary seems to be around 70 because it wasn't quite as easy as some of the easiest papers. I could be way off but think the boundaries are a reasonable indication of that paper

Reply 171

YonRamires

1

Original post by farryharnworth

Are you sure that is wrong? That's how I interpreted the question.
It says "The bullet travels a distance b inside the block before coming to rest relative to the block."
I took that to mean "In the time from when the bullet enters the block to when it comes to rest relative to the block, it travels an absolute distance of b."
I did wonder at the time, because I can see both interpretations, but I took that one.

You could be right, I took it to mean that it travels a distance b relative to the block, but I forgot to substract c in the end.

Original post by YonRamires

2: complete, except I got a solution x=5 instead of x=4 on part (ii) (apparently i'm not good at adding and substracting one digit ints)
3: complete, except for checking double roots in the even case in the last part)
6: did parts (i), (ii), and (iii), not (iv)
7 (that was the question w/ four parts and integrals right?): only part (i)
9: complete, but in the last part I calculated the path of the bullet relative to the table (so b+c instead of b), so I got the value of b wrong
12: complete

can somebody estimate my marks pls…

Reply 172

krishdesai7

3

@Zacken I know you must be absolutely sick of going through people's responses and predicting marks, but could you please please do that for me too?

Spoiler

(edited 7 years ago)

Reply 173

Insight314

7

Original post by shamika

They're not set as a multiple of each other (or requiring 21 marks between them). I'm saying the best candidates will find it easy but the 1/2 boundary seems to be around 70 because it wasn't quite as easy as some of the easiest papers. I could be way off but think the boundaries are a reasonable indication of that paper

You mentioned a while ago that you didn't do the DE question when deciding the boundaries and just saw it and assumed it was easy. I feel like first parts were easy but then (iii) required a bit more work and overall the question would kind of take longer time to get through. I don't know if it is only me, I think I spent a bit over 30 minutes on it and I usually do DE questions a bit faster than other questions.

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Reply 174

username1162972

18

Original post by Insight314

You mentioned a while ago that you didn't do the DE question when deciding the boundaries and just saw it and assumed it was easy. I feel like first parts were easy but then (iii) required a bit more work and overall the question would kind of take longer time to get through. I don't know if it is only me, I think I spent a bit over 30 minutes on it and I usually do DE questions a bit faster than other questions.

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I have literally only seen a handful answer that part.

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Reply 175

Insight314

7

Original post by physicsmaths

I have literally only seen a handful answer that part.

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What do you mean?

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Reply 176

Zacken

OP

22

Original post by krishdesai7

@Zacken I know you must be absolutely sick of going through people's responses and predicting marks, but could you please please do that for me too?

Spoiler

16 + 12 + 20 + 18 + 12(?) + 20 > 95, maybe an S.

Original post by Insight314

What do you mean?

Very few people successfully did (iv) of Q6.

Reply 177

Insight314

7

Original post by Zacken

16 + 12 + 20 + 18 + 12(?) + 20 > 95, maybe an S.

Very few people successfully did (iv) of Q6.

Nah, I skipped that one. I thought physicsmaths was referring to (iii). How many marks was that anyway? I assume 5 max but I have no idea how much work had to be done for it.

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Reply 178

username1162972

18

Original post by Insight314

Nah, I skipped that one. I thought physicsmaths was referring to (iii). How many marks was that anyway? I assume 5 max but I have no idea how much work had to be done for it.

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Around 7.

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