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# How was Edexcel S2? watch

1. (Original post by Leekey)
You only HAD to use the continuity correction once but if you decided to use the normal instead of the poisson for an earlier question then you should have done it twice.

I used the poission Yay thank you
2. Is it just me, or is everyone else thinking the grade boundaries are going to shoot up for S2 this year...
3. (Original post by Mysticmin)
Is it just me, or is everyone else thinking the grade boundaries are going to shoot up for S2 this year...
Don't say that, I'll lose all confidence in getting that B.
4. (Original post by Leekey)
Don't say that, I'll lose all confidence in getting that B.
Ha ha, no worries, with that paper everyone will pull off over 90%, and edexcel will kick themselves are being unable to discern which people they'll chuck over the A grade boundary.
5. (Original post by DaKe)
yea that's rite. The median(1.4) was greater then the mean (1.21111? i think) therefore negative skew
I left the answer as 109/90, which my calculator assures me now is 1.2111etc..

I thought that the skew was negative. I got stuck on this question for a while and ended up drawing a sketch to see what was going on. The mode was way over to the right with the mean somewhere to the left, so the tail was pointing towards the negative numbers, so hence negatively skewed.

John
6. Wasnt 2)a) 0.74 rather than 0.54 as many people have said. (2.7+1)/5 = 0.74

Was the one approximated by the normal distribution 0.1847?
7. (Original post by sideshowbob)
Wasnt 2)a) 0.74 rather than 0.54 as many people have said. (2.7+1)/5 = 0.74

Was the one approximated by the normal distribution 0.1847?
It was indeed, because it existed between -1 and 4 (I think) and for P(X<2.7) you must factor in the negative bit of the distribution to five 3.7/5 which is 0.74.

0.1847 looks vaguely familiar but I cant remember to be honest.
8. (Original post by sideshowbob)
Wasnt 2)a) 0.74 rather than 0.54 as many people have said. (2.7+1)/5 = 0.74

Was the one approximated by the normal distribution 0.1847?
i think it should be 1/5 * 2.7 = 0.54
9. 5)b) 0.991
c) 0.9473

anyone else got ^?
10. P(Z>= (21.5 – 17.5)/(Rt 17.5))

= 1- P(Z<= 0.89)

= 0.1847

Agree?
11. i agree
12. (Original post by sideshowbob)
P(Z>= (21.5 – 17.5)/(Rt 17.5))

= 1- P(Z<= 0.89)

= 0.1847

Agree?
Yes, I do remember that one now. I definitely remember the 0.89 bit and the answer looks very familiar.
13. anyone got the exam paper?

14. (Original post by Leekey)
Usually to works like....

-Correct hypothesis
-Correct interpretation of distribution
-Correct probability
-Correct n value
-Correct comparison with sig level
-Correct in rejecting / not rejecting H0
-Correct in interpreting result of rejecting / not rejecting
say i got n value wrong, did correct follow up method but as a result my interpretation was wrong (soley becos of wrong n value) how many marks out of last 4 do u think i might get?
15. (Original post by RussianDude)
i think it should be 1/5 * 2.7 = 0.54
Nah i dont think so mate, cos i did that first but then realised that its u have to do it for -1<=x<=2.7, therefore the difference is 3.7 and so u do 1/5*3.7 which gives 0.74 and not 0.54
16. How many marks would i loose if i forgot about the interpolation in q 6)d)?
17. (Original post by DaKe)
Nah i dont think so mate, cos i did that first but then realised that its u have to do it for -1<=x<=2.7, therefore the difference is 3.7 and so u do 1/5*3.7 which gives 0.74 and not 0.54
my god, why do people make it sooo difficult, ure find the area of the rectangle so length of base x length of height....so (2.7 - -1) x 1/5 = 0.74
ITS OBVIOUS
...lets stop discussing it....
18. (Original post by RussianDude)
How many marks would i loose if i forgot about the interpolation in q 6)d)?
interpolation? do u mean the contingency thing? if so u lose one mark for not showing u subtracted 0.5 and then one mark for the actual answer. otherwise it SHOULD be method marks you pick up - going from past paper experience
19. continuting i mean, damn business studies revision on the brain!! grrr
20. CONTINUITY even!! im so glad i didnt have to write that in my english lit. exam, id have most certainly spelt it wrong!!

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