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Is this the hardest A Level maths exam question?

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Original post by IrrationalRoot
I feel like if there's a handful of 'high end' questions this will just equate to worse performances all round and thus more scaling which will result in 100s (or close to) for even those students who couldn't do the trickier questions. So it seems more or less impossible to discriminate at the top end with A Level results.


That's a fair observation; any mathematics exam has to cope with the highly skewed upper tails of the ability distribution in this subject. Much ink has been spilled over the question of how to organize maths exams at school level, but I can't help thinking that the current system has some serious drawbacks.

For example, for anyone going on to study Maths, Physics, CS, Engineering, Economics, etc. the current A-level Mathematics has been barely adequate as university preparation in recent years. Many first year university courses (in the "hard" sciences" ) now include what amounts to remedial mathematics (and we've gone to the 4 year undergraduate masters system partly as a reflection of losing much of the first year to this).

Yet there seems to be a need for, what in America would be called, a "liberal arts" qualification at school level for those not going on to the mathematical sciences at university; maybe a padded-out and modified additional maths (GCSE) course in the sixth form.

So I think I'm for splitting the subject, as it's taught and examined, more appropriately for the needs of those studying it.
Original post by IrrationalRoot
I feel like if there's a handful of 'high end' questions this will just equate to worse performances all round and thus more scaling which will result in 100s (or close to) for even those students who couldn't do the trickier questions. So it seems more or less impossible to discriminate at the top end with A Level results.

One possible solution is to introduce grades "above A*" (but arguably you should just have an AEA exam at that point).

FM can get even more problematic if you want to be fair across different A-levels. An A grade in normal maths is almost a prerequisite for doing even decently in FM.
Original post by Gregorius

Yet there seems to be a need for, what in America would be called, a "liberal arts" qualification at school level for those not going on to the mathematical sciences at university; maybe a padded-out and modified additional maths (GCSE) course in the sixth form.

So I think I'm for splitting the subject, as it's taught and examined, more appropriately for the needs of those studying it.

What I think's tricky is that A-level grades have become almost weaponized; if this additional course "isn't a full A-level", I can see a lot of people avoiding it. Conversely, if it is an additional A-level, I can see a lot of people saying "why do the current A-level and risk getting a poor grade when I can do the liberal-arts-A-level instead?".

I do suspect things will settle down a bit as people (and examiners) get used to the new system, but it's going to be an interesting teething period.
As far as the manipulation of ii) goes I haven't seen any examples of anything similar in the textbook questions. I don't yet have any experience of university exams but I'd imagine that their papers remain at a constantish difficulty each year (feel free to correct me here), so although the manipulations are definitely more difficult, students have lots of past examples to familiarise themself with so they're not so taken aback in a real exam.

I think I worded it badly in the previous post but lots of people do just do A-Level Maths because its seen as a "smart subject" and they think it looks "good".

Physics is another subject that's definitely been made more difficult since 2016 and I think German has too a bit (although that's of little relevance here). IDK if A-Levels need to be made more difficult in order to prepare students better for uni as the majority of people say that A-Levels are already harder than 1st year uni (obviously not true for "elite" courses but they're in a small minority).

@Notnek sorry for derailing the thread a bit but I can't find or remember any such difficult exam questions. Would you be interested in textbook questions too?
Original post by DFranklin
The thing is, the main thing people have been objecting to (in this thread) is the manipulation in (ii). Anyone doing the topics you mention (possible exception of CS) is going to be dealing with far more difficult manipulations during their course. It's like the removal of calculus from A-level physics, when there's no way you're going to be doing physics/engineering at university without doing lots and lots of calculus!

I kind of hope A-Level Maths isn't done to show "you're confident with working with numbers", because IMHO it's actually pretty poorly suited to that. (If you're not going on to the courses you describe, I think it extremely unlikely you'll ever be using trig identities, any non-trivial calculus, etc.)

I do take your point about not scaring people of A-level maths (and I can certainly see exams like this doing so!). But at the same time, if it's going to prepare you for university, it has to be more challenging than many are comfortable with. I don't know if the difficulty of the other A-levels is changing at the same time?
(edited 4 years ago)
Reply 44
Original post by Dequavius

@Notnek sorry for derailing the thread a bit but I can't find or remember any such difficult exam questions. Would you be interested in textbook questions too?

I couldn't think of any harder A Level exam question which is why I created the thread :smile: If you know of textbook questions that are harder then please post them.
Original post by DFranklin
What I think's tricky is that A-level grades have become almost weaponized; if this additional course "isn't a full A-level", I can see a lot of people avoiding it. Conversely, if it is an additional A-level, I can see a lot of people saying "why do the current A-level and risk getting a poor grade when I can do the liberal-arts-A-level instead?".


Agreed. It would have to be a full A-level, and it would have to be a qualification that demonstrated useful skills and abilities different from those of "straight" maths. Speculation mode on: the analogy that I'm thinking about here is with philosophy as an academic subject at degree level. It's well liked by quite a few employers, as it's thought to show an ability to reason in ways that are applicable in difficult circumstances. Is there a sort of quantitative equivalent, where you can demonstrate useful conceptual understanding, without too much of the technical side?


I do suspect things will settle down a bit as people (and examiners) get used to the new system, but it's going to be an interesting teething period.


Agreed.
Original post by Dequavius
As far as the manipulation of ii) goes I haven't seen any examples of anything similar in the textbook questions.
Definitely have seen things like this before (at equivalent of A/S level!), but my A-levels were a long time ago.

But just to be explicit here (but using variables instead of numbers to make the TeX easier): the term T_k containing p^k in (p+q)n(p+q)^n is (nk)pkqnk\binom{n}{k} p^k q^{n-k} and then to derive

TkTk+1=(nk)pkqnk(nk+1)pk+1qnk1=(nk1)!(k+1)!q(nk)!k!p=(k+1)q(nk)p\dfrac{T_k}{T_{k+1}} = \dfrac {\binom{n}{k} p^k q^{n-k}}{\binom{n}{k+1} p^{k+1} q^{n-k-1}} = \dfrac{(n-k-1)!(k+1)!q}{(n-k)!k!p} = \dfrac{(k+1)q}{(n-k)p}

is not at all unreasonable to ask at this level IMHO (particularly when you're given the desired answer).
This is a good idea IMO, but I think there would still be a negative stigma against it - people may consider it as the maths A-Level for less able students - and therefore students would just stick to the traditional course anyway. Though once it is more established this probably won't be an issue.
Original post by Gregorius
Agreed. It would have to be a full A-level, and it would have to be a qualification that demonstrated useful skills and abilities different from those of "straight" maths. Speculation mode on: the analogy that I'm thinking about here is with philosophy as an academic subject at degree level. It's well liked by quite a few employers, as it's thought to show an ability to reason in ways that are applicable in difficult circumstances. Is there a sort of quantitative equivalent, where you can demonstrate useful conceptual understanding, without too much of the technical side?



Agreed.


With regards to scaling, UMS doesn't exist in the new exams anymore so the top end of students achieving 95+ would still be distinguishable from the merely "good" students scoring in the 80s. @IrrationalRoot
Original post by Gregorius
Agreed. It would have to be a full A-level, and it would have to be a qualification that demonstrated useful skills and abilities different from those of "straight" maths. Speculation mode on: the analogy that I'm thinking about here is with philosophy as an academic subject at degree level. It's well liked by quite a few employers, as it's thought to show an ability to reason in ways that are applicable in difficult circumstances. Is there a sort of quantitative equivalent, where you can demonstrate useful conceptual understanding, without too much of the technical side?

I think what's tricky about this is that I feel what you'd need to be able to test is "practical application", and without a suitable background in the "practical course" that's very difficult.

To unpack that a little: there's obviously a lot of cross-over between computing and maths, and I think a lot of people would benefit from learning how to solve mathematical problems on a computer (or conversely, use maths to solve problems that arise in computing). But at the same time, how side-tracked do you want to get with teaching people computing during a maths A-level, and why prioritize computing over physics, or economics, or engineering, all of which would have similar claims.

Arguably, you could specifically aim at the same people who do things like "business studies" A-level as they're the one's most likely to struggle with the current A-level anyhow.
(edited 4 years ago)
Original post by Dequavius
With regards to scaling, UMS doesn't exist in the new exams anymore so the top end of students achieving 95+ would still be distinguishable from the merely "good" students scoring in the 80s. @IrrationalRoot

Oh. That's a very good thing imo, as long as they keep the difficulty levels of the papers consistent. So no more 75% raw = 100 UMS in C4 lol.
Reply 50
Original post by IrrationalRoot
Oh. That's a very good thing imo, as long as they keep the difficulty levels of the papers consistent. So no more 75% raw = 100 UMS in C4 lol.

Unfortunately keeping the difficulty levels consistent will probably lead to better grades as students/teachers get more used to the new spec and have lots of past papers to practice with. I hope that the exam writers try hard to make questions that require good understanding and not just familiarity with the exam, which was the problem with the old spec.
Original post by Notnek
Unfortunately keeping the difficulty levels consistent will probably lead to better grades as students/teachers get more used to the new spec and have lots of past papers to practice with. I hope that the exam writers try hard to make questions that require good understanding and not just familiarity with the exam, which was the problem with the old spec.


I mean consistent from some point onwards. If there's no scaling then it's simply unfair to allow to difficulty of the papers to vary greatly from year to year. Well unless the grade boundaries vary too, but I'm not up to date enough with this stuff to know whether they do or not.
Original post by Gregorius
Yes, it is a relatively recent subject; but no, all the basic terms are well defined!

What I'm getting at is, for instance:

1) Where is Q2 for a population of size n = ...
a) 5
b) 10
c) 100
d) 1000
2) What is an outlier? (And what is a fence?)
3) What is the co-efficient of skewness?
4) When should the median be preferred to the mean ?
5) When should the variance be preferred to the IQR?

All of these are from a Year 1 Stats books or a 2018 A-Level Paper. I'm not sure any of them have definitive, or even clear, answers.
Original post by Surfer Rosa
What I'm getting at is, for instance:

1) Where is Q2 for a population of size n = ...
a) 5
b) 10
c) 100
d) 1000
2) What is an outlier? (And what is a fence?)
3) What is the co-efficient of skewness?
4) When should the median be preferred to the mean ?
5) When should the variance be preferred to the IQR?

All of these are from a Year 1 Stats books or a 2018 A-Level Paper. I'm not sure any of them have definitive, or even clear, answers.


...and all standard stuff...
is this as or a2?
Apart from 1a) and b) maybe, (as I said) I don't think there are definitive, or even clear, answers to these questions. Do you? If so, what are they?
Original post by Gregorius
...and all standard stuff...
Reply 56
I think I might have found a question that may be more difficult!!

IMG_20190523_191404.jpg
Reply 57
Original post by Gent2324
is this as or a2?

It was in an A Level paper but parts (ii) and (iii) only require Year 1 knowledge (and also (i) if you use trial and error on your calculator).
Original post by Surfer Rosa
Apart from 1a) and b) maybe, (as I said) I don't think there are definitive, or even clear, answers to these questions. Do you? If so, what are they?

I hope I don’t seem obstructive here, but I’m genuinely puzzled about your puzzlement. May I turn the question around and ask why you think these are not well defined? Have you seen different sources with contradictory answers? (Remember my remark that I’m appalled at the way stays is taught at school level; things do get put right later on!)
Original post by Surfer Rosa

2) What is an outlier? (And what is a fence?)


An outlier is any observed data point inconsistent (in a probabilistic sense) with the underlying probability model in use for an analysis. A fence is a criterion for identifying outliers in a particular situation (and may be constructed in different ways according to the context).


3) What is the co-efficient of skewness?


Third central moment divided by the 3/2 power of the second central moment.


4) When should the median be preferred to the mean ?


In several situations where the mean may not adequately represent the central tendency of the data (if there is a central tendency). For example if the mean is likely to be skewed by outliers in a sample; or in a population context where high degrees of skew tend to obscure what you want the data to tell you (modelling income is a good example here).


5) When should the variance be preferred to the IQR?


That's a question that needs to be re-phrased: "what's the best way to describe the spread of the data?" If what you've got looks close to normal, variance is king; if it is symmetric but has outliers, IQR; if it's highly skew use the triple lower quartile, median, upper quartile (for example. The nastier the distribution, the more numbers you might need to describe its spread: all the deciles, for example).

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