A grouped data set has the following distribution.
Class interval (kg): 0–10 10–20 20–30 30–40
Frequency: 8 15 15 7
Both the classes 10–20 kg and 20–30 kg have the same highest frequency. Which class should be taken as the modal class for further calculation?
(a) 20–30kg
(b) Both 10–20kg and 20–30kg
(c) 10–20kg
(d) No unique modal class can be determined