The Student Room Group

Edexcel S2 - 27th June 2016 AM

Scroll to see replies

For question 7d I got 41.875 but then for some stupid reason rounded it to 41.82 so will I lose the mark because I rounded wrong? Will this affect me getting the marks in the second part? Thanks :smile:
55.5-0.2n / (0.16n)^0.5 = 1.75
55.5-0.2n = 0.4*1.75n^0.5
3080.25-0.04n^2 = 0.49n
308025 - 4n^2 = 49n
4n^2+49n - 308025 = 0
.....
....
.... n = 82. something or 66. something
how did people get 225?
what was that hypothesis testing question i think it was the last part of question 2 or 3
Reply 783
I just put n =225 because in all questions I done before that were similar, they always squared the positive root
Original post by NamelessPersona
If you square both sides you treat it as a bracket


how many marks will i lose?
Reply 785
Original post by KFC_Fleshlight
55.5-0.2n / (0.16n)^0.5 = 1.75
55.5-0.2n = 0.4*1.75n^0.5
3080.25-0.04n^2 = 0.49n
308025 - 4n^2 = 49n
4n^2+49n - 308025 = 0
.....
....
.... n = 82. something or 66. something
how did people get 225?
would be root 0.16n not squared
can anyone remember the question for Q2 ??
Original post by gameofthrones1
how many marks will i lose?


I would say you would get at least 4, an M1 for using normal approx, an A1 for half cc, and an M1 and A1 for getting to 55.5-0.2n = 1.75*sqrt(0.16n)
How were you meant to do the last two questions on the paper?
Original post by bulkybros100
How were you meant to do the last two questions on the paper?


Use E(x) for a discrete distribution as sum of xf(x) and you get around 41.875 I think

Edit: E(x) = 50(27/40) + 25(13/40) = 41.875

you would then go on to say that if he sold n bags he would expect 41.875n pounds, but if he removed staples he would get 0.8n*50=40n.
As 41.875>40, he should not remove staples.
(edited 7 years ago)
Original post by iMacJack
F(3)=1
F(2)=0

Then simultaneous



Posted from TSR Mobile


Original post by Yua
I done it by integrating and making it equal 1, so working out the area under the graph

then F(3) =1

then simultaneous

****, im an idiot
Thanks anyway lads
Original post by NamelessPersona
Use E(x) for a discrete distribution as sum of xf(x) and you get around 41.875 I think


Do you think I would lose a mark for getting 41.875 then accidentally rounding this to 41.82? Thanks :smile:
Reply 792
Original post by bulkybros100
How were you meant to do the last two questions on the paper?

(1-0.325)50 + 0.325(25) = E(X) = 41.88

if he removes staples then because 20% less bins you do 0.8(50) = 40

40<41.88

so he should not remove staples as he'd make less money
Original post by TheSammy2010
My answers, idk if they are right

Q1,
Mean= 1.41
Variance= 1.4419
Probabilities; 0.7769, 0.1378, 0.1516

Q2,
N=60
0.0133
0.0159
Do not reject Ho (using binomial tables)

Q3,
0.75
151π/3

Q4,
K=1/9

Q5,
N=225

Q6,
P(M=5)= 0.3
P(M=6)= 0.29
P(M=7)= 0.12

N=11

Q7,

Mean= 1.2
Var= 1.92
P(X>3)= 0.3250
£41.88 per bin

He shouldn't as the mean profit of bins would be £40


Question 2 the hypothesis test was 0.2236 which is more than 0.01 therefore accept null hypothesis

Question 3 it was 0.5 not 0.75

Question 4 n was 57

Rest are right



Posted from TSR Mobile
Original post by economicss
Do you think I would lose a mark for getting 41.875 then accidentally rounding this to 41.82? Thanks :smile:


I wouldn't think so but I'm not entirely sure

Edit: oops misread what you rounded to, yeah I think you would lose a mark
What we thinking on grade boundaries then?
Reply 796
Original post by Rey Mysterio
What we thinking on grade boundaries then?


65= A
Original post by Rey Mysterio
What we thinking on grade boundaries then?


Pretty high, probably similar to last year
Original post by TheBigBo
It was n and sqrt(n) so the roots of the quadratic are equal to the sqrt of n and then you square the positive one as sqrt(x)≥0


Omg I spent so long on that question thinking that n couldn't possibly be 15!!! Forgot that it was root(n) 😂
I just took a SS of my answers in word - I can't figure out how to formatt on this reply box! XD Here is a neater version of what I wrote - Please Tell Me if I got any wrong.Answers.png
EDIT: For Q1 a) I wrote 1.44 for the mean - This is just a typo - I actually wrote 1.41. Which seems right.
(edited 7 years ago)

Quick Reply

Latest