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Math Help - Statistics - Question on Frequency

  1. #1
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    Exclamation Statistics - Question on Frequency

    I have this question on Frequency, but I've forgotten how to do it. Here's the question:



    The lengths of girls' hair, in a particuler school, is recorded in the table below:

    Length (cm)........... 0-5.......6-10.......11-15.......16-25.......26-50
    Frequency ............. 22........ 27 ..........31........... 54.......... 35
    Frequency Density

    a) Which is the modal class?
    b) How many of the girls are outside the modal class?
    c) Draw a histogram showing this data.
    d) Estimate the number of girls whose hair is less than 8cm in length.


    So, please help, I haven't got long eft to do it. Links or you posting help would be great. Thanks
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  2. #2
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    a) The 16-25cm class is the modal class as it is the most frequent.
    b) 115 girls are outside the modal class (22+27+31+35 = 115)

    The histogram would be fairly easy to draw, but I have no idea how you would do d.
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  3. #3
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    Question

    For the histogram, do you plot the frequency or the frequency density? And for the frequency density, is it

    Code:
    e.g. for the 0-5 class
     
    22 / 5 = 4.4
     
     
    for the 16-25 class
     
    54 / 9 = 6
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  4. #4
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    I would just plot the frequency:
    Attached Thumbnails Attached Thumbnails Statistics - Question on Frequency-histogram.gif  
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  5. #5
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    Quote Originally Posted by xbxbeckyxbx View Post
    I have this question on Frequency, but I've forgotten how to do it. Here's the question:



    The lengths of girls' hair, in a particuler school, is recorded in the table below:

    Length (cm)........... 0-5.......6-10.......11-15.......16-25.......26-50
    Frequency ............. 22........ 27 ..........31........... 54.......... 35
    Frequency Density

    a) Which is the modal class?
    b) How many of the girls are outside the modal class?
    c) Draw a histogram showing this data.
    d) Estimate the number of girls whose hair is less than 8cm in length.


    So, please help, I haven't got long eft to do it. Links or you posting help would be great. Thanks
    (d):-

    As 8 is the centre of the 6-10 class a rough estimate of the number of
    girls with hair length less than 8, in this class is half the number in the
    class, so our estimate of the total number with hairlength less than 8cm
    is the number in the 0-5 cm class plus half the number in the 6-10 class,
    or 22+27/2 = 35.5

    RonL
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