Hey there! Sign in to join this conversationNew here? Join for free

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%

    Offline

    2
    ReputationRep:
    (Original post by NotNotBatman)
    No,  F(x) =P(X\leq x), it wouldn't really matter in continuous distribution, but just stick to less than or equal.
    Thankyou!
    Offline

    1
    ReputationRep:
    (Original post by fpmaniac)
    If you do poisson for any question, the probability you find from that, is that always a fixed probability.
    Sorry! Just saw this now, I think notifications are messed up. And yes it is in S2 so you are able to the same with any other situation given !
    Offline

    0
    ReputationRep:
    would I get penalised for integrating with respect to x instead of t when working out the cdf?
    Offline

    3
    ReputationRep:
    Please can someone explain question 1b https://57a324a1a586c5508d2813730734...%20Edexcel.pdf Thanks
    Offline

    19
    ReputationRep:
    (Original post by daviid1562)
    would I get penalised for integrating with respect to x instead of t when working out the cdf?
    They probs wouldn't care if you use x but might as well use some other variable just to avoid confusion, otherwise you're treating x as both a variable and a particular fixed value
    Offline

    0
    ReputationRep:
    (Original post by 13 1 20 8 42)
    They probs wouldn't care if you use x but might as well use some other variable just to avoid confusion, otherwise you're treating x as both a variable and a particular fixed value
    Thanks. I just got used to writing it with respect to x from the beginning
    Offline

    19
    ReputationRep:
    (Original post by daviid1562)
    Thanks. I just got used to writing it with respect to x from the beginning
    One way is just make one of the xs capital and one of the xs small as it's less change
    Offline

    20
    ReputationRep:
    Pleas e someone help me 😭
    I've posted this four times
    Question:
    6aii

    I don't understand why we are looking at the upper critical value and not the lower critical value as it says minimum

    Attachment 556929

    MS: Attachment 556931










    Posted from TSR Mobile
    Offline

    13
    ReputationRep:
    (Original post by Music With Rocks)
    Yeah you can be asked to work out the variance through integration (for uniform distribution) , which is basically the proof
    Oh right thank you!
    Offline

    1
    ReputationRep:
    (Original post by economicss)
    Please can someone explain question 1b https://57a324a1a586c5508d2813730734...%20Edexcel.pdf Thanks
    Hi just done that question so thought i'd chip in!

    Because its in 48 hours lambda become (1.6)

    since that period greater than or equal to 1 cars are caught you work out the probability of 1-P(X=0) to find the probability

    hope that helped sorry i have no idea how to do the symbols!
    • Very Important Poster
    • Thread Starter
    Offline

    21
    ReputationRep:
    Very Important Poster
    (Original post by Bloom77)
    Pleas e someone help me 😭
    I've posted this four times
    Question:
    6aii

    I don't understand why we are looking at the upper critical value and not the lower critical value as it says minimum

    Attachment 556929

    MS: Attachment 556931










    Posted from TSR Mobile
    Your question is more to do with 6ai rather than 6aii, but as they are in parts.. :dontknow:

    the test above is testing solely whether lambda (the rate of visits or whatever) should be greater, so there is no need to look in the lower region because we're not testing whether lambda is actually smaller (it is a one sided test, basically).

    The 'minimum' is just the minimum value in the critical region found as a result, which is 11. You could have 20 visotors or 40 or even 60000 (theoretically, but very, very, slim). but the minimum (the first value) where the hypothesis is rejected is when X=11. anything less than 10 and you keep the original lambda, so it is insignificant.
    Offline

    0
    ReputationRep:
    https://57a324a1a586c5508d2813730734...%20Edexcel.pdf

    June 2006 question 7
    why is it binomial distribution?
    Offline

    18
    ReputationRep:
    If anyone feels **** about tomorrow, just remember I started revision an hour ago

    Offline

    15
    ReputationRep:
    Just to clarify, the MODE is the X value that gives the highest Y value, right? So you give the x coordinate not the y coordinate?
    Offline

    18
    ReputationRep:
    (Original post by iMacJack)
    Just to clarify, the MODE is the X value that gives the highest Y value, right? So you give the x coordinate not the y coordinate?
    Yes in the pdf
    Offline

    0
    ReputationRep:
    can someone check june 2006 question 7a and tell me why it is a binomial and not a poisson?>
    Offline

    3
    ReputationRep:
    (Original post by Ellie_k98)
    Hi just done that question so thought i'd chip in!

    Because its in 48 hours lambda become (1.6)

    since that period greater than or equal to 1 cars are caught you work out the probability of 1-P(X=0) to find the probability

    hope that helped sorry i have no idea how to do the symbols!
    Thanks so much! I don't suppose you could help me with question 4f here please https://57a324a1a586c5508d2813730734...%20Edexcel.pdf The mark scheme says it is symmetrical and so P(1<x<2)= 11/36 also but I don't understand why! Thanks
    Offline

    18
    ReputationRep:
    (Original post by economicss)
    Thanks so much! I don't suppose you could help me with question 4f here please https://57a324a1a586c5508d2813730734...%20Edexcel.pdf The mark scheme says it is symmetrical and so P(1<x<2)= 11/36 also but I don't understand why! Thanks
    It's a quadratic graph so it's symmetrical about it's minimum/maximum. Since 2 is the middle, and you're given the area between 2 and 3, it must be the same as between 1 and 2
    Offline

    5
    ReputationRep:
    (Original post by Abc321zxc)
    can someone check june 2006 question 7a and tell me why it is a binomial and not a poisson?>
    You're told that 1 in 5 bowls are defective. That implies that the probability of a bowl being defective is 0.2.
    • Very Important Poster
    • Thread Starter
    Offline

    21
    ReputationRep:
    Very Important Poster
    (Original post by Abc321zxc)
    can someone check june 2006 question 7a and tell me why it is a binomial and not a poisson?>
    Please post a link to the question.

    A binomial distribution usually implies a cap. Whereas with Poisson, like measuring rate of customers, theoretically there is no cap on the number of customers that could come in a period of time. The binomial for example is different, because if you're tossing 20 coins it is impossible to get 25 or 30 heads, something that a poisson distribution would imply.
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.