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

1. Can anyone tell me what the reasoning for the mean and standard deviation was in question 5)f
2. (Original post by Angus09)
but because it was 14mm to 70 subshine or whatever it was isnt that against the correlation since r was negative
14mm to 70 fits the correlation
if you used the data they give to calculate mm and minuets it was something like 9mm and 50-60 sunshine, so 14mm and 70 sunshine reasonably fits the correlation
3. Sort of unofficial markscheme for S1
http://www.thestudentroom.co.uk/show....php?t=4166725
4. (Original post by logicmaryam)
Hey guys I've got my answers here:

Predicting 63+ is an A and not lower because it wasn't that bad of a paper. Theory questions threw me off a bit though.

Q1. 11 total i think
a) was Sdd or something (3)
b) wiggles is the response variable as it changes depending distance (1)
c) r = 0.722 + 0.014d
d) d= 350 sub in so w = 5.6 ish?
Q2 Sarah one
a) equation is 2p + q = 0.5
b) a= 0.175 b= 0.15
c) idkd) E(R) = 1/E(X) so 0.45?
e) Sarah wins = 0.475 Rebeccawins= 0.375

Q3 with frequencies?
a) heigh of bar and width igot something like 34cm and 1cm?
b) show that Syy is … (1) didn’tdo this right lol
c) PMCC
d) SD
e) What were the other questions?

Q4 Hotel one
a) 0
b) t =0.03
c) u = 0.22
d) 0.45 and 15/37
e) diners 16? Some people say 33

Q5
a) median 3.47
b) SD = 0.689?
c) mean proof 3.43
d) Probability baby wasunder 3kg something like 0.2546
e) explain the use ofthe model? (2)I said that althoughthe range chosen was appropriate as mean was 3.43 for both and SD was close tothe calculated one, there is negative skew as median>mean so not good to use this model as mean and SD are affected by skew.
f) effect of adding baby weight of 3.43 on (3)
i) mean – I said staysthe same because I sneakily calculated it , because the frequency becomes 51and value is within range or something
ii) SD – the SDincreases? Don’t remember. Because there are more values to be accounted for inthe calculation so spread is increased?

Q6.
a) 0.0668 men took over 300 min to run
b) needs to run below 206.33 minutes to be in 20% of people who finish first
c)
d) the mew one0.18/0.5 = 0.36 (3)

Let me know what I'm missing and I've done wrong as well as the marks for each if you remember
It was NOT that easy how the heck it can be 63+ for 80UMS ._. oh well maybe for you but not for most of the people here
5. (Original post by anna096)
Do you remember how many marks this question was?
2 marks
6. i think 58 will be an A, as this paper was a bit more difficult than the 2015 paper. I probably got about 45
A - 58+
B - 53
C - 45
D - 39...
7. (Original post by thuphammm)
It was NOT that easy how the heck it can be 63+ for 80UMS ._. oh well maybe for you but not for most of the people here
Sorry haha, I messed up a few questions so it was much easier for me but I do think boundaries wont be lower than 60 for A
8. (Original post by moshe015)
Wasnt saras chance 0.65 and rebeccas 0.2???

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sorry if someone's already replied to you but you put -2 as higher than -1/2 (making sarah win an extra one) lol, i did that at first then was like o wait
9. (Original post by alexesl17)
they all seem pretty correct, the only difference to me was that i said the guy with the normal distribution for the babies was fine to use that equation since the mean and median of the data were pretty close indicating a symmetrical distribution
Yes that's what I said too
10. (Original post by Apolexian)
14mm to 70 fits the correlation
if you used the data they give to calculate mm and minuets it was something like 9mm and 50-60 sunshine, so 14mm and 70 sunshine reasonably fits the correlation
Ah, crap, were they not in the same base then? that's so annoying.
11. (Original post by logicmaryam)
Hey guys I've got my answers here:

Predicting 63+ is an A and not lower because it wasn't that bad of a paper. Theory questions threw me off a bit though.

Q1. 11 total i think
a) was Sdd or something (3)
b) wiggles is the response variable as it changes depending distance (1)
c) r = 0.722 + 0.014d
d) d= 350 sub in so w = 5.6 ish?
Q2 Sarah one
a) equation is 2p + q = 0.5
b) a= 0.175 b= 0.15
c) idkd) E(R) = 1/E(X) so 0.45?
e) Sarah wins = 0.475 Rebeccawins= 0.375

Q3 with frequencies?
a) heigh of bar and width igot something like 34cm and 1cm?
b) show that Syy is … (1) didn’tdo this right lol
c) PMCC
d) SD
e) What were the other questions?

Q4 Hotel one
a) 0
b) t =0.03
c) u = 0.22
d) 0.45 and 15/37
e) diners 16? Some people say 33

Q5
a) median 3.47
b) SD = 0.689?
c) mean proof 3.43
d) Probability baby wasunder 3kg something like 0.2546
e) explain the use ofthe model? (2)I said that althoughthe range chosen was appropriate as mean was 3.43 for both and SD was close tothe calculated one, there is negative skew as median>mean so not good to use this model as mean and SD are affected by skew.
f) effect of adding baby weight of 3.43 on (3)
i) mean – I said staysthe same because I sneakily calculated it , because the frequency becomes 51and value is within range or something
ii) SD – the SDincreases? Don’t remember. Because there are more values to be accounted for inthe calculation so spread is increased?

Q6.
a) 0.0668 men took over 300 min to run
b) needs to run below 206.33 minutes to be in 20% of people who finish first
c)
d) the mew one0.18/0.5 = 0.36 (3)

Let me know what I'm missing and I've done wrong as well as the marks for each if you remember
I got similar answers to you for most
12. Well at least you got part i right!
13. For the probability of Sarah/Rebecca winning did anyone else do P(X>1/X) and rearrange to get P(X^2>1) and P(X^2<1) for each of them winning? I think I got like 0.2 for P(R win) and I believe (may be mistaken) 0.65 for P(S win)
14. (Original post by logicmaryam)
Sorry haha, I messed up a few questions so it was much easier for me but I do think boundaries wont be lower than 60 for A
I think I got around low 70s and it was definitely harder than last year which was like 58 for an A?
15. (Original post by AlphaQuark)
For the probability of Sarah/Rebecca winning did anyone else do P(X>1/X) and rearrange to get P(X^2>1) and P(X^2<1) for each of them winning? I think I got like 0.2 for P(R win) and I believe (may be mistaken) 0.65 for P(S win)
Yh i did
16. (Original post by CaiusMartius)
I think I got around low 70s and it was definitely harder than last year which was like 58 for an A?
last year 59 was an A. This year will probably be 58
17. P= 0.175 Q=0.15

Or possibly the other way around

(Original post by Patrick Gekko)
also wondering this.
what did you get for p and q, out of interest?
18. (Original post by Megan3245)
last year 59 was an A. This year will probably be 58
Yeah agreed. Tbh atm only marks I think I lost were on the writing ones hahaha
19. I got 10/25 and 12/25 for the Sarah and Rebecca question??
20. (Original post by CourtlyCanter)
I said the Standard Deviation remained unchanged as the weight of the baby does not deviate from the mean weight of the babies.

I also said the Mean remained unchanged as it is the same as the mean weight of the 50 babies before the addition of this new baby.

Not sure if I got them right though. Someone please confirm or point out where I went wrong.
Wow I wrote the exact same points as you for both of them lol

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