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Edexcel S2 - 27th June 2016 AM Watch

  • View Poll Results: How did you find the Edexcel S2 exam?
    Very hard
    145
    14.71%
    Hard
    331
    33.57%
    Normal
    293
    29.72%
    Easy
    152
    15.42%
    Very easy
    65
    6.59%

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    (Original post by iMacJack)
    Normal Approx I did this can someone tell me what I'd lose

    X-B(n,0.2)

    Goes to

    Y-N(0.2n,0.16n)

    P(Y>55) = P(Y>55.5) = P(Z>(55.5-n)/0.4rootn)) = 0.0401 (whatever t was) Then I did p(z<=(55.5-n)/0.4rootn) = 0.9699

    therefore (55.5-n)/0.4rootn = 1.75

    I then solved a quadratic and got the value of N as 51. The slip I made was misreading my own writing and putting 55.5-n instead of 55.5-0.2n

    How many dropped??


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    probably 2-3 marks
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    (Original post by target21859)
    Worrying won't help but the wait to find out what I got is killing me
    Same!
    I forgot to square 15 to get 225 and i messed up on the circle question, everything else was pretty good I reckon ive got around 67-70 dependant.
    I really need A* after screwing up M2 despite getting 95 last year on D2
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    (Original post by river222)
    Same!
    I forgot to square 15 to get 225 and i messed up on the circle question, everything else was pretty good I reckon ive got around 67-70 dependant.
    I really need A* after screwing up M2 despite getting 95 last year on D2
    Yeah I need A* in FM. My exams went so well last year but this year I really screwed up. I know I can do it but not under exam conditions. I always make really stupid mistakes.
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    (Original post by ISAAQAHELP)
    oh didn't see that prob one accuracy mark. they might not notice like i did but i am doing 2 stuff at once so i wasn;'t paying attention
    Yeah... there's no chance of them not noticing haha


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    (Original post by ISAAQAHELP)
    none the accept both decimal and percentage
    0.1 isn't the correct significance level so he would lose a mark at least. it was 1% not 10%
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    i did q5 by trial and error so how many marks would i get? i also correctly changed the binomial to normal and did a continuity correction but couldn't get the correct answer unless i did trial and error?
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    (Original post by target21859)
    only 80?
    Well, S2 is sort of unpredictable. That mark would easily get you a solid A with 84+ UMS on IAL June 14 or June 15, but would be a high B on UK 15 or IAL Jan 16... I say relax until the grade boundaries are released - even then, you could still be severely underestimating yourself!
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    Does anyone know if @kprime2 is DOIN model answers


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    (Original post by igotohaggerston)
    How many marks was the P(7<R<10) question
    What was the answer to this question????!
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    (Original post by iMacJack)
    Does anyone know if @kprime2 is DOIN model answers


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    He said he would in another thread, probably tomorrow.
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    (Original post by Ayman!)
    Well, S2 is sort of unpredictable. That mark would easily get you a solid A with 84+ UMS on IAL June 14 or June 15, but would be a high B on UK 15 or IAL Jan 16... I say relax until the grade boundaries are released - even then, you could still be severely underestimating yourself!
    When are grade boundaries released???
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    (Original post by Ayman!)
    Well, S2 is sort of unpredictable. That mark would easily get you a solid A with 84+ UMS on IAL June 14 or June 15, but would be a high B on UK 15 or IAL Jan 16... I say relax until the grade boundaries are released - even then, you could still be severely underestimating yourself!
    I did calculate the absolute minimum I could get. I think I could get up to 69 (that would be great). Last year I was a lot more confident about what I was going to get. Got 198/200 in C3 and C4 so no problem there for A* in normal maths and I thought FM was in the bag as well...
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    (Original post by Dentistry101)
    What was the answer to this question????!
    I just did the area so (10-7)*probability. I can't rightly remember what the probability was, maybe 1/4? If so it would just be 3/4.
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    0.5
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    (Original post by igotohaggerston)
    0.5
    Was that a reply to me??
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    (Original post by Jack_Linaker)
    I just did the area so (10-7)*probability. I can't rightly remember what the probability was, maybe 1/4? If so it would just be 3/4.

    But the distribution was U~[5,9] so would it not be 2 x 0.25??
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    The distribution was [5,9] so it would've been 0.25*(9-7)=0.5
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    (Original post by ISAAQAHELP)
    THIS IS THE QUESTION FOR THE normal APPROX.

    X-B(N,0.2) USING NORMAL APPROX AND GIVEN THAT P(X>55)=0.0401
    FIND N

    AND ANSWER:
    X-B[N,0.2]= W-N[X,Y"] X IS MEAN Y" IS VARIANCE " MEANS SQUARED

    P(X>55)=P[W>55.5)=P(Z>([55.5-X]/Y)=0.0401

    P(Z<([55.5-X]/Y)=1-0.0401=0.9599

    USING TABLE

    (55.5-X)/Y=1.75
    55.5-X=1.75Y
    1.75Y+X=55.5 NOW USING THE BINOMIAL PARAMETERS
    WE CAN FIND Y AND X IN TERMS OF N
    X=0.2N
    Y"=0.2*0.8N Y"=0.16N Y=0.4N! WHERE !=SQUARE ROOT
    SO 1.75(0.4N!)+0.2N =55.5
    0.7N!+0.2N=55.5
    0.2N+0.7N!-55.5=0 NOW SOLVE THIS USING QUADRATIC FORMULA
    YOU GET N!=15 OR (-18.5)
    SO N = 225 OR 342.25 BUT WE ARE DEALING STUDENTS
    SO N=225 ONLY
    don't KNOW WHY PEOPLE ARE GETTING 200

    I know I did wrong. I used 55 not 55.5 , worked out 223 and 340. I didn't reject 340..... How many marks I will lost?
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    (Original post by Dentistry101)
    But the distribution was U~[5,9] so would it not be 2 x 0.25??
    God dammit you're right fml
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    Could someone link me the unofficial scheme?
 
 
 
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