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Unit 6: Dispersion: Meaning and Characteristics, Absolute and Relative Measures of Dispersion including Range...


                                                                                                     Notes
                                        Largest Value – Smallest Value
                     Coefficient of Range =
                                        Largest Value + Smallest Value
                                      or

                                      L – S
                                      L + S

            Individual Series
            Example 1:  Find out absolute and relative dispersion of range from the following observations:
                        Marks: 63, 68, 71.5, 83, 50, 27, 64, 38, 40
            Solution:   Absolute measure of Range  = Largest – Smallest
                                                = 83 – 27 = 56 marks
                                                  Largest – Smallest
                                 Relative Measure =
                                                  Largest + Smallest

                                                  83 – 27  56
                                                =        =    = 0.509
                                                    +
                                                  83 27   110
            Example 2:  Calculate Range and its coefficient of the following series:
               S. No.     1      2      3      4     5      6      7      8     9     10

               Values    391   384    591    407    672   522    777    733   2488  1490

            Solution:                    Largest = 2488, Smallest = 384,
                                          Range = L – S
                                           2488 – 384
                                                = 2104
                                                  L – S
                              Coefficient of Range =
                                                  L + S

                                                  2488 – 384  2104
                                                =          =      = 0.7325
                                                      +
                                                  2488 384   2872
            Example 3:  The yearly income of a person for the last ten years in given below. Find the range
                        and its coefficient.
                    Year         2001  2002  2003  2004  2005  2006  2007  2008  2009  2010

              Income (‘000 Rs.)   40    30    80   100   80    90    120  110   130   150

            Solution:                    Range = L – S from the data, L = 150, S = 30.
                        ∴                Range = 150 – 30 = 120
                                                 L – S
                              Coefficient of Range =
                                                 L + S

                                                 150 – 30  120
                        or                     =         =
                                                    +
                                                 150 30    180
                                               = 0.66




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