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Percentiles
For raw data , first arrange the n observations in increasing order. Then the xth percentile is given by For a frequency distribution the xth percentile is given by Where Example 15
= 35 +(38-35)
= 35 + 3 = 37.25 kg
= 11th item + (12th item – 11th item) = 55 +(58-55) = 55 + 3 = 55.75 kg
Example 16
The frequency distribution of weights of 190 sorghum ear-heads are given below. Compute 25th percentile and 75th percentile.
Solution
For P25, first find out , and for , and proceed as in the case of median. For P25, we have = 47.5. The value 47.5 lies between 34 and 69. Therefore , the percentile class is 80-100. Hence, Similarly, Class = 120 +14.33 =134.33 g.
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Last modified: Friday, 16 March 2012, 7:03 PM