A 'more than' cumulative table of weekly study time in hours reads — more than 0: 60, more than 5: 54, more than 10: 42, more than 15: 24, more than 20: 10, more than 25: 0. Which class contains the median?

Difference the consecutive entries to recover the class frequencies 6, 12, 18, 14, 10, which total 60. The ordinary 'less than' cumulative counts are then 6, 18, 36, 50, 60, and n/2 = 30 is first reached at 36, which belongs to the third class. So the median lies in 10–15.