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# Edexcel S1 - 15th June, 2016 [Exam Discussion] watch

1. (Original post by tazza ma razza)
what you didn't know about mean<median = negative skew ?

besides, it will tell you if you need to use this, otherwise learn page 67 of the textbook
Well I thought the mode thing was needed as well :/
2. (Original post by JT423)
Yes, any way of proving it's a positive skew is valid. The mark scheme are using: IF
Mean<Median<Mode-- Negative skew
Mean=Median=Mode-- Symmetrical (no skew)
Mean>Median>Mode-- Positive skew
Gotcha, thanks!
3. why am i sat reading this instead of actually revising fgs
4. (Original post by anndz3007)
mean > median >mode => postive skew
im not sure about your method cus i dont usually use it, only if the question gives you the formula, but the mark scheme allows it for alt so it wont be the case
Mark scheme doesn't say specifically, but apparently any valid method that proves it is right. Thanks!
5. In in in in.
6. Is there no June 2015 (R) paper?

Also, wonder what the chances of statistical modelling coming up.. I don't really know it that well
7. (Original post by JT423)
the method you used is right. 0.0875=7/80
however how did you get 0.25 for P(b/\c) (maybe venn diagram was wrong). P(b/\c) is also 7/80 (4+3/80) so as they're equal, they're statistically independant
I got 1/4 for p(b//c)
because 28 people do chem. And out of these 28, 7 of them do bio so
7/28 = 1/4.
My Venn was right? I'm probably making a really silly misconception idk
8. (Original post by Siddhart1998)
I got 1/4 for p(b//c)
because 28 people do chem. And out of these 28, 7 of them do bio so
7/28 = 1/4.
My Venn was right? I'm probably making a really silly misconception idk
there are 80 people in the study, not 28, hence the probability of doing both is 7/80..
9. (Original post by Uberphuq)
Is there no June 2015 (R) paper?

Also, wonder what the chances of statistical modelling coming up.. I don't really know it that well
Just write
-helps improve understanding of real world problem
-simplifies real world problem
-real world problem can be analysed
10. do we have to know the process of statistical modelling???
11. Is there a summary for what affects PMCC, standard deviation, mean and quartiles?
12. Can someone explain question 5b on the January 2016 IAL paper. I don't really know how to use given that with normal distribution. I thought that if it is the probability of getting a medal given the probability of a certificate it would be P(M/C)=P(MnC)/P(C)
So I get that the probability of the Certificate is 0.0446 but how do I find the intersection between certificate and medal? The answer just uses the probability of getting a medal over the probability of getting a certificate P(M)/P(C) but I don't get why P(M)=P(MnC) ???
Thank you
13. 67 - 69 for 90 UMS i reckon
14. (Original post by miranda_1998)
do we have to know the process of statistical modelling???
Yes. There are 7 stages.
15. (Original post by angellll)
Guys, do you know where I could possibly get the June 2015 paper from?
Here.
Attached Images
16. s1june2015.pdf (297.5 KB, 80 views)
17. (Original post by neil20143)
Don't lie, you can't have finished a stats paper in less than 30 minutes, even if you got 70/75!
i'll let you in on a little secret - having a graphical calculator with certain settings allows you to solve varience / normal distrubutions and do basic probability faster than what I can do without it...
18. (Original post by miranda_1998)
do we have to know the process of statistical modelling???
yes
19. (Original post by Electrify)
Is there a summary for what affects PMCC, standard deviation, mean and quartiles?
quartiles aren't affected by a general addition/removal of data - it depends on the value eg if it is below/above the mean/median etc (easiest to figure out)

for the mean, adding/subtracting affects the mean. multiplying i think does (would need an example to confirm this)

for varience (SD^2) multiplying/dividing affects it ie multiplying by 2 leads to it increasing by 4 (I am pretty sure)

PMCC nothing affects it
20. (Original post by tazza ma razza)
compared to the other papers, it is easy. Try june 10 (80 ums was 55/75 compared to 60 for june 13r)
need hard papers. Whats the hardest youve done?
21. (Original post by govandpolitics)
need hard papers. Whats the hardest youve done?
imo june 10

the others with the full 90 mins, you can do and get 100

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