In a survey, scores of 60 students were grouped as follows:
Class (scores) 0–20 20–40 40–60 60–80 80–100
Frequency 8 15 20 10 7
Using an ogive to locate the median, in which class interval does the median score fall?
(a) 60–80
(b) 40–60
(c) 20–40
(d) 80–100