Edexcel S2 - 27th June 2016 AM

OP

Original post by mehtj006

Hi everyone, just wanted to ask if i can have this split C1234 D1 S2 FP12 S3 S1 M1 M2

I'm not sure if works slightly differently for IAL, but for normal maths, in A-level maths you can only have a 1 and a 1 (two different types) or a 1 and a 2 of the same type. So D1 and S2 isn't allowed - if S2 goes to A-level maths, S1 must also go to A-level maths.

But the exam board works out how your grade works and makes it the best it can in both, basically.

Reply 142

ketwizard

1

I predict definitions will come up. Also this paper is going to be more challenging than usual, edexcel are increasing the difficulty of m2 and s2 as too any people are getting A's even if they cant do C3 or C4 maths to even B standard!

Reply 143

AlphaArgonian

12

http://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2013/Exam%20materials/Question-paper-Unit-S2-(6684)-Paper-1R-June-2014.pdf

Can someone explain Q6c, and Q7c-e, please? I obtained all other marks but these ones are bugging me.

Reply 144

Superbubbles

5

Need help on 2015 paper q3b anyone know??

Reply 145

Superbubbles

5

Does anyone know how to do 3b on 2015 paper please I know it's super easy but I've forgotten how to find the mode :/

Reply 146

thenextchemist

What are the hardest ever questions from normal papers of s2?

Posted from TSR Mobile

Reply 147

bat_man

Original post by Superbubbles

Does anyone know how to do 3b on 2015 paper please I know it's super easy but I've forgotten how to find the mode :/

sketch the graph. see where the highest point is. The x value of where the point is, thats your mode.

Reply 148

taysc

Hi Sean,

I really don't understand this question at all. Its from the Jan 13 paper, I was wondering if you could please help with it? I don't get how they set up the F(x) function and so I misunderstood the rest of the question
Screen Shot 2016-06-25 at 11.31.43.png

Thanks @SeanFM

Reply 149

OP

Original post by taysc

Hi Sean,

I really don't understand this question at all. Its from the Jan 13 paper, I was wondering if you could please help with it? I don't get how they set up the F(x) function and so I misunderstood the rest of the question
Screen Shot 2016-06-25 at 11.31.43.png

Thanks @SeanFM

Original post by SeanFM

Ah yes, I remember this question :lol:

It is not a PDF. It has a relationship with the CDF though, which is what you have to work out.

Read the line 'the probability that the mosquito survives for 'more than t days is...' and then think about what the CDF is (hint: less than or equal to is the key word for a CDF).

See post above :tongue:

Reply 150

OP

Original post by AlphaArgonian

http://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2013/Exam%20materials/Question-paper-Unit-S2-(6684)-Paper-1R-June-2014.pdf

Can someone explain Q6c, and Q7c-e, please? I obtained all other marks but these ones are bugging me.

With the CDF, you can find the proportion of children whose estimate is ... blah blah blah.

So that's the proportion (or probability, if you like) of children that are right.. and you have 80 people, so you would expect ... many to be right out of 80.

Reply 151

taysc

Original post by SeanFM

See post above :tongue:

P ( X > T) = 1- P ( X ≤ T)

Is that what it means?

It still kind of confuses me

Thanks for the quick reply

Reply 152

OP

Original post by taysc

P ( X > T) = 1- P ( X ≤ T)

Is that what it means?

It still kind of confuses me

Thanks for the quick reply

Precisely.

If we take a discrete distribution (no difference if it's continuous, but let's keep it simple), say X is a binomial distribution with p = p (some probability, doesn't matter, n= 20, say).

And we pick a random number in that distribution, say 8. Then every number that the distribution can take (ranging from 0 to 20) is either going to be greater than 8, or less than or equal to 8. It sounds obvious/strange but we can use that. There is no value that X can take that isn't less than or equal to 8, or greater than 8, so

P(X \leq 8) + P(X > 8) = 1

as those two statements cover every number in X. You can generalise that for any x value from X,

P(X \leq x) + P(X > x) = 1 \Rightarrow 1 - P(X>x) = P(X \leq x) = CDF.

(edited 7 years ago)

Reply 153

Superbubbles

5

Original post by bat_man

sketch the graph. see where the highest point is. The x value of where the point is, thats your mode.

Is sketching the graph the only way to do it? It's only 1 mark

Reply 154

OP

Original post by Superbubbles

Is sketching the graph the only way to do it? It's only 1 mark

Please link the question in the future :redface:

it saves everyone else some time :tongue:

A graph of the pdf is one way of finding the mode. The other (albeit the same idea) is finding the x value for which the pdf takes the highest value, because that value has the highest chance of occuring so in a sample, you'd expect it to be the most common number (the mode). Sometimes you can spot this from the PDF without any calculations.

Reply 155

zombaldia

Would you guys reccomend revising s1 before this exam? Did it last year but fair to say I don't really remember much of it. Done alright in s2 papers but I feel like edexcel could easily slip a question that requires s1 knowledge in this year

Reply 156

bat_man

Original post by Superbubbles

Is sketching the graph the only way to do it? It's only 1 mark

sketching the graph is really easy. it should take less than a minute. It also allows you determine whether the mode is a stationairy point, where youd have to differentiate the pdf, and set it equal to 0, to find out the mode that way. But yeah, thats the only way i think.

Reply 157

bat_man

Original post by zombaldia

Would you guys reccomend revising s1 before this exam? Did it last year but fair to say I don't really remember much of it. Done alright in s2 papers but I feel like edexcel could easily slip a question that requires s1 knowledge in this year

its probably good for maybe a probability type question, or a skew question. Im lucky that i resat s1 this year lol.

Reply 158

OP

Original post by zombaldia

Would you guys reccomend revising s1 before this exam? Did it last year but fair to say I don't really remember much of it. Done alright in s2 papers but I feel like edexcel could easily slip a question that requires s1 knowledge in this year

Maybe a recap on skew (somewhere in the back of my mind says it's been asked in S2 before, but not sure on that one).

Also the definition of conditional probability - specifically something like this: where X is a distribution, t is some time (that X depends on) and h is a positive number)

P(X>t+h | X > t ) = \frac{ P( X > t +h \cap X > t)}{P(X > t)} = \frac{P( X > t + h)}{P(X>t)}

. The key bit being that X > t +h intersect X > t is X > t + h, as that is the 'tighter' of the two inequalities.

I haven't defined x, t and h etc but you'll see if it if it comes up (and it has done in one or two past papers).

Lastly, the normal distribution if you aren't at all confident with it, but it can come from doing practice in S2 instead.

Reply 159

zombaldia