The following table gives the age distribution of 80 members of a club. Cumulative frequencies only are supplied.
Age (years)
0–10
10–20
20–30
30–40
40–50
50–60
Cumulative frequency
6
17
35
52
68
80
(a) Define the cumulative frequency of a class in a grouped frequency distribution.
(b) Explain the rule used to decide which class interval will contain the median when the total number of observations is known.
(c) Without calculating the median value, identify the median class for the above data and write the cumulative frequency of the class just preceding it. Give a brief reason for your answer.