I swear 6b was like 176.336 or something? If the mean was 200 minutes how can the fastest 20% be P(X<206) like you got? Surely P(X<206) would be >0.5(Original post by veldt127)
Ok, I managed to get all my answers stored in my calculator at the end, this is what I got. Not 100% sure on all of them, but we can compare.
Question 1Spoiler:Question 2Showa. Show that
b. W  can't remember reasoning
c. 0.994
d. 0.0772 + 0.0142d
e. i. 5.69
ii. Reliable as the data was interpolated; it was within the rangeSpoiler:Question 3Showa. 2p + q = 0.5
b. q = 0.15
c. p = 0.175
d. 2.12
e. 0.45
f. i. 0.475
ii. 0.375Spoiler:Question 4Showa. 2.35
b. Show that
c. 133.9  possibly 131.9
d. 0.754
e. Increase  I tried using the variables from the new week and recalculating r, and it was higher than the original. I said because the values were both higher than the means; I'm not sure at all on this one.
Spoiler:Question 5Showa. 0
b. t = 0.03
c. u = 0.22
d. i. 0.45
ii. 15/37
e. 33 people have dinner (40*0.18) + (37*(15/37))Spoiler:Question 6Showa. Width 0.5, Height 17
b. 3.47 (median)
c. i. Show that
ii. Standard deviation = 0.680  possibly 0.689
d. P(W<3) = 0.2546
e. No  the mean is not equal to the median suggesting asymmetrical skew18% of babies were less than 3kg, but her model predicted 25.46%
f. i. Mean remains the same as the new value is the mean
note: mean might decrease as it adds a value to the 33.5 group.
ii. The standard deviation decreases as the variance decreases with a new value close to the meanSpoiler:Showa. 0.0668
b. 206  The lowest 20% of times were the fastest 20% of runners.
c. 0.36
You are Here:
Home
> Forums
>< Study Help
>< Maths, science and technology academic help
>< Maths
>< Maths Exams

Edexcel s1 June 2016 unofficial mark scheme
Announcements  Posted on  

Would YOU be put off a uni with a high crime rate? First 50 to have their say get a £5 Amazon voucher!  27102016 

 Follow
 121
 15062016 17:42

 Follow
 122
 15062016 17:44
(Original post by SANTR)
So you divided each of the observations by 1 and then multiplied the 'same' probabilities with each corresponding 'new' observation i.e. 1/ each observation?
therefore you take the reciprocal of each observation in the pdf and using knowledge of the expectation E(x), which is the sum of the P(x=x) multiplied by each observation x then you should get a value for E(S). Which btw was P(X=S)
so it's about how u interpret the question and manipulate so x would be s and from there if you know what your doing you should end up with the right answer does anyone remember the table the x values not the P(X=x)? 
 Follow
 123
 15062016 17:45
Anyone know the marks for the other questions? I remember a few. It would be useful to add to the first post.
Bee wiggle question
Response variable (1 mark)
Work out regression line (3 marks, may have been 4)
Sarah rebecca prob distribution
Make an equation with p and q (1 mark)
Find p (2 mark)
Hence find q (1 mark maybe 2??)
Find var x (2 mark, maybe 3 cos u had to find E(x squared) aswell)
Find E(R) (3 marks)
Probabilities of them winning a game (4 marks) split into two parts
Rainfall question
Find Syy (1 mark lol)
Work out R (2 marks)
State effect on pmcc with reason (2 marks)
Baby question
Work out width/height of bar (3 marks)
Linear intepolation for median (3 marks)
Show estimate of mean is... (2 marks)
Standard deviation (2 marks)
P(x<3) (2 marks i think)
Was shyan right to use normal distribution (3 marks)
Hotel question
Question about probability of booking a breakfast without room was (1 mark)
Working out the value of t was (4 marks) and then
Working out the value of U was (2 marks.)
The conditional probabilities of the people eating dinner question (2 marks for each part so 4 marks overall)
The part about estimating the amount of people from the coach who had dinner was (2 marks)
Normal dist. question about marathon
1st part (3 marks)
Finding how fast he can run to be in top 20% (3 marks)
Finding probability of X<u30x<u (3 marks)
Only have 59/75 marks here written down, anyone else remember the other 16? They are missing from the bee question and the rainfall question, I think i got the other ones completedLast edited by uk_shahj; 15062016 at 17:47.Post rating:1 
 Follow
 124
 15062016 17:46
(Original post by igotohaggerston)
We are talking about Edexcel here 
 Follow
 125
 15062016 17:47
(Original post by Katieramsay)
How did everyone get the probability for Sarah and Rebecca wining. I got 0.4625 and 0.4450 so clearly I've got it wrong but I don't understand how?? 🤓🤓
You treated it as one value of X picked for sarah, then a different value picked for Rebecca. A lot of calculation and cases later you got your answers.
You might get marks for a special case misread, as your question is actually harder but testing the same maths. 
 Follow
 126
 15062016 17:48
(Original post by Roadman)
I swear 6b was like 176.336 or something? If the mean was 200 minutes how can the fastest 20% be P(X<206) like you got? Surely P(X<206) would be >0.5
I remember the question being the probability between mew + 30 and mew  30.
The probability W < mew + 30 was 0.82 so P(W<mew 30) and P(W> mew+30) = 0.18. So bit in middle was 10.36 = 0.64.
I'm pretty sure I'm wrong considering everyone got 0.36. I guess I just read the question wrong as I was half asleep. Does anyone remember the exact wording of the question?
Edit  I ****ed up this paper big time. How didnt i notice that question was conditional probabilityLast edited by 666kappa; 15062016 at 17:49. 
 Follow
 127
 15062016 17:48
(Original post by Katieramsay)
How did everyone get the probability for Sarah and Rebecca wining. I got 0.4625 and 0.4450 so clearly I've got it wrong but I don't understand how?? 🤓🤓 
 Follow
 128
 15062016 17:50
(Original post by 666kappa)
Did anyone else get 6c as 0.64 not 0.36?
I remember the question being the probability between mew + 30 and mew  30.
The probability W < mew + 30 was 0.82 so P(W<mew 30) and P(W> mew+30) = 0.18. So bit in middle was 10.36 = 0.64.
I'm pretty sure I'm wrong considering everyone got 0.36. I guess I just read the question wrong as I was half asleep. Does anyone remember the exact wording of the question? 
 Follow
 129
 15062016 17:51
(Original post by 666kappa)
Did anyone else get 6c as 0.64 not 0.36?
I remember the question being the probability between mew + 30 and mew  30.
The probability W < mew + 30 was 0.82 so P(W<mew 30) and P(W> mew+30) = 0.18. So bit in middle was 10.36 = 0.64.
I'm pretty sure I'm wrong considering everyone got 0.36. I guess I just read the question wrong as I was half asleep. Does anyone remember the exact wording of the question?

 Follow
 130
 15062016 17:52
(Original post by PrinceAli)
The bit in the middle didn't have much to do with the question I'm afraid. You had to work out 18/50 as it was p(anb)/p(b) with a being chance of less than u  30 and b being less than u. 
 Follow
 131
 15062016 17:53
(Original post by studentsixth)
Actually Edexcel have always been nice with stats grade boundaries, having touched 56 last year in the IAL paper and a few times in 20102011. So I wouldn't rule out 56 or 57 (doubting 55 though)
Posted from TSR MobilePost rating:1 
 Follow
 132
 15062016 17:56
(Original post by studentsixth)
I got exactly that! 
 Follow
 133
 15062016 17:56
(Original post by 666kappa)
Did anyone else get 6c as 0.64 not 0.36?
I remember the question being the probability between mew + 30 and mew  30.
The probability W < mew + 30 was 0.82 so P(W<mew 30) and P(W> mew+30) = 0.18. So bit in middle was 10.36 = 0.64.
I'm pretty sure I'm wrong considering everyone got 0.36. I guess I just read the question wrong as I was half asleep. Does anyone remember the exact wording of the question?
Edit  I ****ed up this paper big time. How didnt i notice that question was conditional probability
as u said P(W< mew30) is 0.18 due to symmetry then u divide that by P(W<mew) which is 0.5 which gives u 0.36 
 Follow
 134
 15062016 17:58
(Original post by Mr T Pities You)
Check back through the thread for a pic. I know what you did wrong: the question said that a computer selected a single value of X, then both Sarah and Rebecca are allocated a score based on this using X or 1/X.
You treated it as one value of X picked for sarah, then a different value picked for Rebecca. A lot of calculation and cases later you got your answers.
You might get marks for a special case misread, as your question is actually harder but testing the same maths. 
 Follow
 135
 15062016 18:05
(Original post by Katieramsay)
Thanks do you have a picture??
(And you can faintly see my wrong answer rubbed out  the same error you made! When will I learn to read the question properly?)Last edited by Mr T Pities You; 15062016 at 18:07.Post rating:1 
 Follow
 136
 15062016 18:05
(Original post by azizadil1998)
Mate there was a VERY similar question in one of the past papers, fortunately did it the night before hahah  You just had to subtract the value they gave from 1 to get 0.18, and "P(X<u)" is just the mean, and the mean represents 0.5 in a normal distribution model; therefore 0.18/0.5 = 0.36.
You're so lucky no way! Now youve said it, makes perfect sense ty so much but ugh im kicking myself fml 
 Follow
 137
 15062016 18:21
(Original post by Roadman)
I swear 6b was like 176.336 or something? If the mean was 200 minutes how can the fastest 20% be P(X<206) like you got? Surely P(X<206) would be >0.5Post rating:1 
 Follow
 138
 15062016 18:28
(Original post by uk_shahj)
Anyone know the marks for the other questions? I remember a few. It would be useful to add to the first post.
[...]
Only have 59/75 marks here written down, anyone else remember the other 16? They are missing from the bee question and the rainfall question, I think i got the other ones completed(Original post by Patrick Gekko)
Q1: 2,1,2,4,2Q2: 1,3,2,2,3,4Q3: 3,1,2,2,2Q4: 1,4,2,4,2Q5: 3,2,3,3,3,3Q6: 3,3,3those were the marks for each part of the question.Post rating:1 
 Follow
 139
 15062016 18:46
(Original post by Roadman)
You weren't looking for the bit in the middle. It was P(W< mew30 I W< mew)
as u said P(W< mew30) is 0.18 due to symmetry then u divide that by P(W<mew) which is 0.5 which gives u 0.36Last edited by jbaten; 15062016 at 18:51. 
 Follow
 140
 15062016 18:52
The last time they asked the conditional probability question it was:
1 mark for stating the p(X<u30)/p(X whatever it was)
1 mark for putting the correct numbers into it
1 mark for the answer
There was also a mark available for if you treated it like an independent event like in probability.
Write a reply…
Reply
Submit reply
Register
Thanks for posting! You just need to create an account in order to submit the post Already a member? Sign in
Oops, something wasn't right
please check the following:
Sign in
Not got an account? Sign up now
Updated: September 11, 2016
Share this discussion:
Tweet
TSR Support Team
We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.