variable : 0-10, 10-20, 20-40, 40-60, 60-80, 80-100 frequency : 8, 1, 22, 25,8,7. calculate median when unequal classes are given

Dear student,

 

classes	frequency	cumulative frequency
0-10	8	8
10-20	1	9
20-40	22	31
40-60	25	56
60-80	8	64
80-100	7	71

total (N)

71

median =   ΣFrequency  
​​​​​​                          2
             =     71 
                     2
             =    35.5
​​​​
median class = (40-60)

Median = L +   (N/2)-cf     x i
                            f
where,   L = Lower Limit of that median class i.e. 40
             N = Total no. of frequency i.e. 71
            cf = cumulative frequency of that median class i.e. 56
              i = difference between lower and upper limit of median class i.e. (60-40=20)
              f = frequency of that class i.e. 25

Median = 40 +   (71/2)  -  56    x  20
                                 25
             = 40 +   (-20.5)    x  20
                             25
             = 40 - 16.4
             =  23.6