Answer the following questions on the concept of range for grouped data.
(i) Define the term “range” for a set of data.
(ii) When data are presented in the form of class intervals, describe how you would identify the maximum and minimum values needed to determine the range.
(iii) The following frequency distribution shows the marks obtained by 40 students in a weekly quiz:
Marks (out of 20): 0–4, 5–9, 10–14, 15–19
Without carrying out any calculation, state which two numerical values (with their appropriate units) you would extract from the table in order to compute the range of the marks.