(i) Maximum number of hours students studied = 17
Minimum number of hours students studied = 1
Range = Maximum value – Minimum value
=17-1 = 16
Class width (size) = 5
Number of intervals = 16/5 = 3.2
i.e. 4
(ii) Number of children, who studied for 15 or more hours in a week are 2 in number.