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# Arsey's S1 Edexcel Summer 2013 Model Solutions BOTH PAPERS Watch

1. I thought I died in S1 - I only got wounded. I thought I did atrociously in D1 - I got hung upside down, beaten and then repeatedly kicked in the genitals..

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2. I know I’m retaking S1 after looking at the model solutions, dropped nearly 15 marks. So, I might as well ask now. If they don’t specify how many decimal places or significant figures they want the answer to, do you chose your own degree of accuracy? For example, in the regression questions you have to find X bar then Y bar then B then A, but A relies on your answer for B and if you’ve done B to say 3dp then A won’t be fully accurate and if you’ve rounded your two means up too, the accuracy is going to slip even more, so is it best to try and stay as accurate as possible, rather than doing to #dp/sf in each stage of your working. Gaahhh, does that even make sense. 
3. (Original post by Arsey)
it doesn't matter, any skew means that you shouldn't use the mean.

I just looked at the fact the data was clustered at the start, hence positive.

mean < median, which also indicates negative skew.

I will have a think about it tomorrow. it is a bit weird.
When I was looking at the data to say if using the mean was sutible I noticed that and thought that one of my results must have been wrong.
4. Hey how many marks would i lose in total for:
1) Not putting on the outliers on the box plot (but i did work them out!!)
2) Doing the Venn Wrong
3) not converting into a percentage
5. (Original post by Arsey)
oh FFS

Arsey do you think a marker might be generous and allow me not putting in values for the interpretation on the regression line just saying as one goes up one goes down?really wanted to kill it with 100%
6. On the last question 6c) i messed up by reading the value of 0.001 of the able instead of 0.01, how many marks would I lose?
7. Did anyone else get 1/10 1/10 3/10 3/10 2/10 for the probability distribution of y?
8. Isn't question 4 data negatively skewed?
( considering the quartiles??)
9. Guys I have a question about the Venn Diagram. Instead of writting out the actual numbers in it, I wrote out the probabilities. In essence, it's correct but will I get the marks or even some of the marks? Thanks
10. I was so nervous I did so sh*t, but this is actually making me feel more confident. Overall, I can see I've lost 4 marks because of me not understanding what the question was asking, and maybe a fw more more.

For question 3d, if we didn't put a 0 in the B circle, but got everything else right, would that lose a mark?
11. How many marks will I lose in total :
1)if i stated only the air temp at 500 and 1000 m instead of working their difference as i didnt read the question properly ,
2) not stating that SD is unaffected when time is minused but saying everything else corrent about mean,median ,iqr.

i think i did all else corrently , may lose 2 mark for 1 probability's small part rest is ok....
12. Is it a must to convert the probability to a percentage in the last question some part to get the mark?

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13. (Original post by davidbaroi)
How many marks will I lose in total :
1)if i stated only the air temp at 500 and 1000 m instead of working their difference as i didnt read the question properly
I think you'll be alright, as the difference between 1000 and 500 is 500 and so you only need to find the temperature change for 500, if that makes any sense?

Besides, it's what Arsesy did in via model answer anyway.. Just worried 'cause I got 7.9 instead of 7.5

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14. Not too bad dropped about 6 marks on 3c, mixing up which one was given. 4A must have been a calculation error on standard deviation; how many marks would that lose me? And 5F I had no idea what it was asking, but apart from that not too bad.
15. Why is question 2a 25? I thought it was the value of q3?

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16. (Original post by Arsey)
Decent paper, every question had been asked before, nothing sneaky or too hard at all.

1. Correlation and regression - pretty easy but took a long time. Part e) will be poorly answered.

2. Box plots - very easy

3. Probability - pretty easy

4. Mean, sd, median, coding - all pretty simple

5. drv - I thought this was easy but I can see it causing problems

6. Normal distribution - standard.

Quite a bit easier than Jan, but S1 boundaries are generally low as a higher prortion of weaker candidates take S1. The highest summer boundary in the last 10 years was 61.

I am going for 62 for an A.

This summer I will upload solutions to the following Edexcel papers:

Core 1;
Core 2;
Core 3;
Core 4;
FP1;
M1;
M2;
S1;
D1;
D2.

I will try to get hold of some solutions for FP2; FP3 and M3.

I don't do S2

All papers will be uploaded in line with site rules (please don't PM me asking when I will I be uploading them).
Arsey, for question 2, you've seemed to have made a mistake, You wrote 14 is an outlier, but seemed to have drew the cross at about 25, please correct me if I misunderstood what you did
17. 73 (+), depends if they like the wording on my interpretations
18. It appears I've dropped around 5-7 marks.
Thanks Arsey.
19. (Original post by yl95)
*Sorry, also, for that wordy question on q5f, I didn't specify that the mean, median, IQR would decrease BY 5MM
Also for question 1), I used the answers in 3s.f. to find the product moment correlation coefficient, do I get the mark?
And also for the last part of the probability question, I did the probabilities in the Venn diagram COMPLETELY wrong but added up (same method) even though I obviously got the wrong answer. Do I get a method mark at all?
is that the one where you had to say how the answers for a) b) c) and d) would change if the results were all shifted by 5? I just put whether they would change or not because it told us not to do any more calculations.... is that wrong?
20. A decent paper. Dropped 12/13 marks because of the Venn diagram and some other stupid mistakes.
Hopefully that is an A !!

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