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

1. LOL i ****ed it like i ****ed c1 and c2
2. Are the model answers up? And if they are can someone give me the link to them?
Thanks
3. (Original post by Angus09)
yh same but i talked about the correlation that alot of rain and alot of sunshine would cause r to become more positive correlation and hence r decreased (got closer to 1) and then also talked about sxy .
i put that since these values support the correlation they would increase the fit of the regression line and so r would become closer to -1
4. (Original post by Angus09)
yh same but i talked about the correlation that alot of rain and alot of sunshine would cause r to become more positive correlation and hence r decreased (got closer to 1) and then also talked about sxy .
coser to -1
5. (Original post by target21859)
Reckon I got 69-72. Bit disappointed personally. Standard deviation stayed the same right?
Pretty sure it reduced because now on average the values were closer to the mean.
6. (Original post by Chengryan96)
4marks but can anyone explain how can they get those answers..?
Well not sure im right but i just multiplied the probabilities together that sarah won to get something like 0.445 and then worked out the probability that they drew +0.445, then 1- (0.445+P(draw) to get P(rebecca won)
7. logicmaryam For the histogram the dimensions were, 0.5 width 17 high
8. (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
post this as a new thread
9. For people asking about the Sarah and Rebecca question, I worked it out by:
R = 1/x S=x (they told you this)
Prob. of Sarah winning is P(S>R) = P(X>1/x) = P(x>1/2) then you must use values from the table
Prob. of Rebecca winning is P(R>S) = P(1/x>X) = P(X<1/2) then you must use values from the table
10. For the first given question in the Venn diagram I got 9/11 0.27/0.33.....
11. (Original post by CaiusMartius)
Pretty sure it reduced because now on average the values were closer to the mean.
But the standard deviation is the sum of x - mean x all squared so your extra term would be 0 so no change.
12. (Original post by KloppOClock)
post this as a new thread
alright
13. Was the height not 5 cm and 0.5cm width tf????
14. (Original post by Apolexian)
i put that since these values support the correlation they would increase the fit of the regression line and so r would become closer to -1
but because it was 14mm to 70 subshine or whatever it was isnt that against the correlation since r was negative
15. (Original post by Angus09)
Well not sure im right but i just multiplied the probabilities together that sarah won to get something like 0.445 and then worked out the probability that they drew +0.445, then 1- (0.445+P(draw) to get P(rebecca won)
Yeah, that's what I got.
16. (Original post by target21859)
Reckon I got 69-72. Bit disappointed personally. Standard deviation stayed the same right?
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.
17. (Original post by Piers456)
For people asking about the Sarah and Rebecca question, I worked it out by:
R = 1/x S=x (they told you this)
Prob. of Sarah winning is P(S>R) = P(X>1/x) = P(x>1/2) then you must use values from the table
Prob. of Rebecca winning is P(R>S) = P(1/x>X) = P(X<1/2) then you must use values from the table
Ah would have done that but panicked in the exam. I just drew a table got the same answer for a but for b I stupidly did 1-part a which is obviously wrong. I should have just the probabilities up arghh.
18. I made an unofficial mark scheme, not 100% sure on all of it, but check it out http://www.thestudentroom.co.uk/show...1#post65799831
19. (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
i said against too. So therefore r would increase ( get closer to 0)
20. (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
Do you remember how many marks this question was?

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