{statics} Kvartil (quartiles) why I didnt get right solution ?

  • Thread starter artiny
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  • #1
artiny
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Homework Statement



On this vector I didnt get the right answer:

x = [ 5 8 10 11 137 ] [/B]
q3: i = (p/100)*n = (75/100)*5 = 3.75 >> 4th in vector is 11
q1: i = (25/100)*5 = 1.25 >> 2nd is 8

in MATLAB is solution
Capture.PNG




Homework Equations




The Attempt at a Solution

 

Answers and Replies

  • #2
haruspex
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Never seen this concept before, but from a little reading at http://au.mathworks.com/help/stats/quantiles-and-percentiles.html it seems that the vector is interpreted as:
1/10 are <= 5
3/10 are <= 8,
5/10 are <= 10
etc.
For the first quartile, we want find how many are <= 0.25. This is done by interpolation between1/10 and 3/10. 0.25 is positioned (0.25-0.1)/(0.3-0.1) along that interval, so gets that share of (8-5):
5 + (8-5)*(0.25-0.1)/(0.3-0.1) = 7.25.
 

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