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    Hi, I’m confused at how you work out the Lower Quartiles & Upper Quartiles when given a set of data (such as 7) where it’s not divisible into 4.

    Here’s the question below:

    “A person recorded the following data during an experiment”

    4 , 6 , 8 , 12 , 15 , 20 , 24

    Calculate:
    - Lower Quartile:
    - Upper Quartile:
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    (Original post by Sam.T.)
    Hi, I’m confused at how you work out the Lower Quartiles & Upper Quartiles when given a set of data (such as 7) where it’s not divisible into 4.

    Here’s the question below:

    “A person recorded the following data during an experiment”

    4 , 6 , 8 , 12 , 15 , 20 , 24

    Calculate:
    - Lower Quartile:
    - Upper Quartile:
    https://math.stackexchange.com/quest...ven-an-even-nu

    I would just go with splitting the data in two (not including median) and find the median of each, as described in post above
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    I’d go with Kevin De Bruynes Method also ^^^
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    (Original post by Kevin De Bruyne)
    https://math.stackexchange.com/quest...ven-an-even-nu

    I would just go with splitting the data in two (not including median) and find the median of each, as described in post above
    So would you have 4,6,8 so the median of this set of data is 6( making the LQ 6) and the median of 15,20,24 would be 20 (making the UQ 20) is this correct?
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    (Original post by Y11_Maths)
    So would you have 4,6,8 so the median of this set of data is 6( making the LQ 6) and the median of 15,20,24 would be 20 (making the UQ 20) is this correct?
    Yes, with the caveat that this is one of two methods, where there is no clear choice between either.
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    (Original post by Kevin De Bruyne)
    Yes, with the caveat that this is one of two methods, where there is no clear choice between either.
    Does this mean that there are 2 potential answers to this question since method 2 would be different? How would you know which one to use?
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    (Original post by Y11_Maths)
    Does this mean that there are 2 potential answers to this question since method 2 would be different? How would you know which one to use?
    It's worse than you think.

    Some years ago, Mr M posted this link: https://ww2.amstat.org/publications/.../langford.html
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    (Original post by BuryMathsTutor)
    It's worse than you think.

    Some years ago, Mr M posted this link: https://ww2.amstat.org/publications/.../langford.html
    That is actually crazy. Now im confused? Which method would they want you to do in an exam?
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    (Original post by Y11_Maths)
    That is actually crazy. Now im confused? Which method would they want you to do in an exam?
    If a question asks for quartiles from a list you should use: \frac{n+1}{4}, \frac{n+1}{2} and \frac{3(n+1)}{4}.

    They give lists where these values come out as integers or *.5 rather than *.25.

    So for a list of 7 numbers you would pick out the 2nd, 4th and 6th.

    For 9 numbers you would want \frac{2^{nd}+3^{rd}}{2}, 5^{th} and \frac{7^{th}+8^{th}}{2}
 
 
 
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