S2 Edexcel Thursday 24th May AM - PAPER & SOLUTIONS IN FIRST POST

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Reply 680

Gibbo81

Original post by Manishex

How about if you put down range? :confused:

Should be fine

This was posted from The Student Room's iPhone/iPad App

Reply 681

exam2k10

Original post by Gibbo81

I reckon 63 for an A so somewhere between 75 and 80

This was posted from The Student Room's iPhone/iPad App

Thanks. Do you know how harshly Edexcel mark?

For example, for question 8) I used a binomial distribution and did X~B(10,0.6) and then did 1-P(X<=1) and got 0.9939. How many marks will I lose?

Reply 682

Gibbo81

Original post by exam2k10

Thanks. Do you know how harshly Edexcel mark?

For example, for question 8) I used a binomial distribution and did X~B(10,0.6) and then did 1-P(X<=1) and got 0.9939. How many marks will I lose?

For which bit?

Reply 683

exam2k10

Original post by Gibbo81

For which bit?

Question 8a) part 2 Cos I reckon I will lose 1 since I got the 1st part right

Reply 684

nicsxox

On question 5b where you had to find E(X), i did that part wrong but on part c) where you to find the variance, i did all the methods right but just used the wrong value of E(x) would I get error carried forward marks? Or would i just lose the marks completely?

Reply 685

andrewpeters

Does anyone guess at whether 66/67 would be enough for 90 UMS?

Reply 686

raheem94

Original post by Gibbo81

...

I failed to understand the sampling distribution question, so i just found the sampling distribution for median rather than range.
How many marks will i lose?

In the last question, last part, i didn't got the right answer but i did the few initial steps correct, ie

P(X<n) \ge 0.9 \implies P(X < n-1) \ge 0.9

, is there a chance that i will get 1 mark for it?

So if i get 2 marks in the sampling distribution question and 1 in the last part of the last question, then i have lost around 6 marks :sad:

.

According to you, what will 69/75 be in terms of UMS?

Reply 687

nakz_

Original post by andrewpeters

Does anyone guess at whether 66/67 would be enough for 90 UMS?

i dont think so, i think u'll need 69 for 90 UMS. reckon 66 is about 85 86

Reply 688

jukebox123

Original post by Arsey

Okay I will later

This was posted from The Student Room's iPhone/iPad App

hey arsey, have you created an M3 thread yet?

Reply 689

FO12DY

Question 6 - for the sampling distribution, was it necessary to draw the table out for probability of the ranges?

I wasn't really sure what to do (apparently we weren't taught it, but people always say that when they're pissed at a question - I've not paid attention in too many S2 lessons to know) but the first thing I did was to draw up a table of probability of x against x being ball numbered one or two (rather than against the range being zero or one). I then wrote out the possible combinations, as Arsey did, and calculated the probability of each.

But was the table showing probability of each range the actual question, so to speak, and what you needed as a final answer? Regardless, I should have got some for working, I'm just interested as to what the question really was.

Fecked up on question 8, too, lol - didn't take (n - 1) off of 50 for the last part. I knew it was wrong I was just running out of time and couldn't get my head around what I was doing in real terms, so I missed the 50. Ah well, I think it was closer to correct than I thought so hopefully there's some method there.

Reply 690

Arsey

Original post by jukebox123

hey arsey, have you created an M3 thread yet?

http://www.thestudentroom.co.uk/showthread.php?t=2014429&p=37798440#post37798440

Reply 691

andrewpeters

Original post by Arsey

http://www.thestudentroom.co.uk/showthread.php?t=2014429&p=37798440#post37798440

Hey Arsey, could you guess at this year's S2 grade boundaries please? Or just what 90/80/70 UMS would be? :smile:

Reply 692

jukebox123

Original post by andrewpeters

Hey Arsey, could you guess at this year's S2 grade boundaries please? Or just what 90/80/70 UMS would be? :smile:

90 ums- 70/75
80 ums- 66/75
70 ums- 60/75

Reply 693

knowledgecorruptz

Original post by jukebox123

90 ums- 70/75
80 ums- 66/75
70 ums- 60/75

!? Serious? Last year it was 67 for 90 UMS...that was a fairly easy paper, tbh, so I reckon this year's will be around there...if not lower...I think 70's a little too high, as quite a few people messed up the sampling distribution q and the last one...just my opinion, tho :smile:

Reply 694

Injin

How many marks would i gain from the sampling distribution question if i did it like this:

(1,1,1)
(1,1,2) ect all the possible samples and then correctly calculated all the probabilities.
For the table i put them as follows
x = (3 ones) (2 ones, 1 two) (2 twos, 1 one) (3 twos)

and then wrote down the corresponding probabilities

Thanks!

Reply 695

Dae93

Original post by Injin

I did EXACTLY what you did. And it's bugging me so much. I'm going to be pessimistic and say 1, possibly two marks but I've heard a few people say 3. I wish Yey had put the work range in bold! Then maybe I wouldn't have overlooked it!

Reply 696

Phenylethylamine_

Original post by Injin

Well, I did the same thing! :rolleyes:

I asked Gibbo (guy who posted the solutions) and he said 3, max 4. I've seen on a lot of mark schemes, they usually give 3 marks for combinations. So, I hope we at least get 3 marks!! Otherwise, it would be a disappointment because we know what to do just missed the word 'range' lol. :colondollar: