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Math Help - Measures of dispersion problem

  1. #1
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    Oct 2009
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    201

    Measures of dispersion problem

    marks number of student
    10-19 2
    20-29 8
    30-39 x
    40-49 13
    50-59 5



    a)given that the first quartile mark is 30.5.Find the value of x





    b)find the total number of students.
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  2. #2
    Member
    Joined
    Jan 2009
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    Punjab, Pakistan
    Posts
    88

    First Quartile

    The first quartile is the point below which 25% of the cases fall and above which 75% of the cases fall


    10-19 2
    20-29 8
    30-39 x
    40-49 13
    50-59 5

    x+13+5 = (2+8)3
    x+18 = (10)3
    x+18 = 30
    x = 12
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