i) Test scores of 20 students for 100 marks are given below
93, 84, 97, 98, 100, 78, 86,100, 85, 92, 55, 91, 90, 75, 94, 83, 60, 81, 95, 77
Range = Maximum value – Minimum value
= 100 – 55 = 45
Length of the class / class interval = 10
[∵ 51 – 60,61 -70]
No. of classes
ii) Modal class : 91 – 100
[ ∵ maximum frequency is 10, which
corresponds to the C.l → 91 – 100]
iii) Median class : 81 – 90
[∵ N/2 occurs at the cumulative frequency 10, which corresponds to the C.I 81 – 90]