At first we neet to sort the initial data
To calculate quartile deviation
"{Q_{dev}} = \\frac{{{Q_{3\/4}} - {Q_{1\/4}}}}{2}"We need to calculate the 1/4 quartile and 3/4 quartile. Because the number of elements in our list is odd, the 1/4 quartile is defined as the average of the median of the "\\frac{{n - 1}}{2}" smallest elements and the median of the "\\frac{{n + 1}}{2}" smalles elements. The median of the first 3 smalles elements "5,9,12" is "9" and the median of the first 4 smalles elements "5,9,12,12" is "\\frac{{9 + 12}}{2} = 10.5" . Thus "{Q_{1\/4}} = \\frac{{9 + 10.5}}{2} = 9.75" . The same procedure we shall do for the 3/4 quartile (but we shall use largest instead smallest). I.e. The median of the first 3 largest elements "15,18,24" is "18" and The median of the first 4 largest elements "12,15,18,24" is "\\frac{{15 + 18}}{2} = 16.5" . Thus "{Q_{3\/4}} = \\frac{{16.5+ 18}}{2} = 17.25" . Now we can calculate the quartile deviation
And we can calculate quartive variation coefficient
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