C.I.
xi
fi
fiixi
c.f
100-120
110
12
1320


12


120-140


130


14


1820


26


140-160


150


8


1200


34


160-180


170


6


1020


40


180-200


190


10


1900


50

 

Σfi = 50

 

Σfixi = 7260

 
(ii) Here the max. class frequency is 14, and the class corresponding to this frequency is 120-140. Model class is 120 - 140,  Class size h = 20f1 = freq. of the model class = 14f0 = 12,   f2 = 8 which lies in the class 120 - 140 l = 120. c.f. = 12, f = 14, h = 20Hence, mean = 145.2    mode = 125  median = 138.6