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Edexcel S3 UK and IAL June 2016 model solutions

Hey!

Edexcel S3 UK June 2016 solutions below. IAL ones are coming in the next post by someone else in a bit. I can't upload the actual paper due to copyright violations but if you don't quite remember what a question was, leave a reply below and I'll jog your memory.

Was a easier than usual paper, I think. Wordy questions might lose people a mark or two. High boundaries.

Edit: Q6(c) should read 3 degrees of freedom instead of 2 and a corresponding chi-squared value of 11.345, the conclusion still stands.
(edited 7 years ago)

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Original post by Zacken
Hey!

Edexcel S3 UK June 2016 solutions below. IAL ones are coming in the next post by someone else in a bit. I can't upload the actual paper due to copyright violations but if you don't quite remember what a question was, leave a reply below and I'll jog your memory.

Was a easier than usual paper, I think. Wordy questions might lose people a mark or two. High boundaries.


Have you got the paper? Im pretty sure question 3c wasn't worth 4 marks...?
Reply 2
Original post by coolguy123456
Have you got the paper? Im pretty sure question 3c wasn't worth 4 marks...?


Yes, I do. And yes, it was 4 marks. To jog your memory, it was asking you to test the spearman positive correlation.
Original post by Zacken
Yes, I do. And yes, it was 4 marks. To jog your memory, it was asking you to test the spearman positive correlation.


Yeah i remember the question, i mis-read the value from the tables so got it wrong, i think i'll lose all 4 marks or do you think i'll get 1-2 marks for stating the correct H0 and H1? Also, is it possible for you to send the paper on pm or are you not allowed to? (completely find if you aren't, I'm just curious) Do you have any predictions for the grade boundaries?
(edited 7 years ago)
Reply 4
Original post by coolguy123456
Yeah i remember the question, i mis-read the value from the tables so got it wrong, i think i'll lose all 4 marks or do you think i'll get 1-2 marks for stating the correct H0 and H1? Also, is it possible for you to send the paper on pm or are you not allowed to? (completely find if you aren't, I'm just curious) Do you have any predictions for the grade boundaries?


You'll get 1 mark for the H0 and 1 mark for the degree of freedom/critical value/stuff. So 2 marks sounds about right. Possibly 3 depending on the markscheme.
Original post by Zacken
You'll get 1 mark for the H0 and 1 mark for the degree of freedom/critical value/stuff. So 2 marks sounds about right. Possibly 3 depending on the markscheme.


But i mis-read the value from the formula booklet or so i think (actually i think i wrote 0.7143 down but must have made a stupid mistake by saying 0.75>0.7143 and messed it up there, but should get 1 mark at least for H0 and H1 hopefully)
Reply 6
Original post by coolguy123456
But i mis-read the value from the formula booklet or so i think (actually i think i wrote 0.7143 down but must have made a stupid mistake by saying 0.75>0.7143 and messed it up there, but should get 1 mark at least for H0 and H1 hopefully)


Yes, but usually you get 1 mark writing the correct conclusion whatever your value of 0.75 or 0.7143 is, as long as the conclusion matches your answer. I'd give you 2 in best-case, 1 in worst-case.
Original post by Zacken
Yes, but usually you get 1 mark writing the correct conclusion whatever your value of 0.75 or 0.7143 is, as long as the conclusion matches your answer. I'd give you 2 in best-case, 1 in worst-case.


Oh right so ECF in a sense. I get you now, because i made the error during the actual "test" but my conclusion matches my test, i should get 1 mark at the end too. Thanks this has calmed me down!
Reply 8
I think i got 73 cri

Posted from TSR Mobile
Reply 9
Original post by coolguy123456
Oh right so ECF in a sense. I get you now, because i made the error during the actual "test" but my conclusion matches my test, i should get 1 mark at the end too. Thanks this has calmed me down!


Yep, precisely! :smile:

Original post by Krollo
I think i got 73 cri

Posted from TSR Mobile


That's a really good mark, well done! But I can imagine how you feel, buckle up, 'dem Tripos ranks that really matter. :wink:
Reply 10
Why did you get 2 degrees of freedom for Q 6c)? Was sure it was 5-1 minus another for the parameter to make 3?
Reply 11
Original post by SHJBHB
Why did you get 2 degrees of freedom for Q 6c)? Was sure it was 5-1 minus another for the parameter to make 3?


5 cells.

1 expected frequency under 5.

Merge.

4 cells.

Estimate parameter.

4-1-1 degrees of freedom.
Reply 12
Original post by Zacken
5 cells.

1 expected frequency under 5.

Merge.

4 cells.

Estimate parameter.

4-1-1 degrees of freedom.


But in your answer the lowest expected frequency is the >=4 box with 10.87, still with 5 cells so I'm not sure why you would merge after that? Sorry if it's staring me in the face but I just can't see it
Reply 13
Original post by SHJBHB
But in your answer the lowest expected frequency is the >=4 box with 10.87, still with 5 cells so I'm not sure why you would merge after that? Sorry if it's staring me in the face but I just can't see it


Oh, it's because I can't count.
Reckon it matters if I use round brackets for the confidence intervals? Shouldn't, should it?
Reply 15
Original post by cjlh
Reckon it matters if I use round brackets for the confidence intervals? Shouldn't, should it?


Doubt it'll matter.

Original post by SHJBHB
...


Fixed, thank you. :smile:
Reply 16
Original post by Zacken
Doubt it'll matter.



Fixed, thank you. :smile:


Are you sure last question was 5 marks??

And if I got everything right apart from inserting the correct z value, do you think I'll get 3 marks?

Also do you think I'll lose a mark for not including % in the confidence interval in the last q?
Reply 17
Original post by Armpits
Are you sure last question was 5 marks??


Yes.

And if I got everything right apart from inserting the correct z value, do you think I'll get 3 marks?


Yep, sounds about right.

Also do you think I'll lose a mark for not including % in the confidence interval in the last q?


Nah.
Reply 18
Hi! Sorry for being late, but here are the answers to the IAL paper -

Spoiler


Questions 1 to 6 (a) were standard, with possibly 2(b) being one of those comment questions you have to understand well to get marks. 6(b) was a conditional probability question which might have caught out a few candidates, but simple to tame if you've done some of this in S1. 7(b) seemed like a discriminator - the expectation algebra was tricky to get and seemed worth a lot for 2 marks. 8(b) is also a question which seemed to have been troublesome for a few.

Overall, a trickier (and more interesting) S3 exam than past years; lengthy as well due to the 8 questions, 2 chi squared tests and the expectation algebra in 7(b). It'd be tough to call boundaries, but seeing as IAL S14 and S15 were 64/69 and 65/70 for the A/A* respectively, I would hope that this paper would be a little lower at 62-63/67-68 since this was much tougher than those years; it probably won't be since S3 always seems to have high boundaries.

I'd like to apologise for my summarised answer on the stratified sampling question, but this shouldn't be an issue to most since it was bookwork anyway. :tongue:

Please do point out if I've made any errors!
Hi,
I made a terrible error when pooling the binomial question. Given that my following test statistics and conclusions suited my mistake, how many marks would I lose for that?
Thx.

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