S2 PDF/CDF quartiles

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  1. snow leopard's Avatar
    • Exalted and Worshipped Member
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    S2 PDF/CDF quartiles
    Q7 (g)

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    The mark scheme says since it's a symmetric distribution, to get Q3 you do 5-1.3
    Where did the 1.3 come from/what is it?
  2. Jin3011's Avatar
    • Peer Of The TSR Realm
    • Location: Karakura | Posts: ∞
    Re: S2 PDF/CDF quartiles
    What exam board is this?
  3. Slumpy's Avatar
    • TSR Idol
    • Location: Scotland
    • Posts: 7,974
    Re: S2 PDF/CDF quartiles
    Using symmetry, the distance from 5 to Q3 is the same as the distance from 1 to Q1, as 1 and 5 are the endpoints. Make sense?
  4. ghostwalker's Avatar
    • Outcast of Imrryr
    • Location: CA13
    Re: S2 PDF/CDF quartiles
    (Original post by snow leopard)
    ...
    If the lower quartile is at 2.3, which is 1.3 above the bottom of the distribution, then the upper quartile is 1.3 below the top of the distribution; if you'll pardon the loose terminology.
  5. Zhy's Avatar
    • Overlord in Training
    • Posts: 3,117
    Re: S2 PDF/CDF quartiles
    I just did this question a few minutes ago!!
  6. snow leopard's Avatar
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    Re: S2 PDF/CDF quartiles
    (Original post by Jin3011)
    What exam board is this?
    Edexcel, why?

    (Original post by ghostwalker)
    If the lower quartile is at 2.3, which is 1.3 above the bottom of the distribution, then the upper quartile is 1.3 below the top of the distribution; if you'll pardon the loose terminology.
    Right I see. My mistake was thinking the bottom of the distribution was 0, when it's actually 1. Thanks
  7. Jin3011's Avatar
    • Peer Of The TSR Realm
    • Location: Karakura | Posts: ∞
    Re: S2 PDF/CDF quartiles
    (Original post by snow leopard)
    Edexcel, why?
    Was just curious
  8. D_Akinola's Avatar
    • New Member
    • Posts: 2
    Re: S2 PDF/CDF quartiles
    Trying to calculate medians and quartiles. If you have multiple functions in your F(x), how do you know which one to equal to 1/2 to find the median, for example?
  9. ghostwalker's Avatar
    • Outcast of Imrryr
    • Location: CA13
    Re: S2 PDF/CDF quartiles
    (Original post by D_Akinola)
    Trying to calculate medians and quartiles. If you have multiple functions in your F(x), how do you know which one to equal to 1/2 to find the median, for example?
    If you already have F(x), then evaluating that function at the end of the interval corresponding to each part definition will tell which is the appropriate part to use.
  10. D_Akinola's Avatar
    • New Member
    • Posts: 2
    Re: S2 PDF/CDF quartiles
    Thanks.
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