The following ‘less than’ cumulative frequency tables show the marks (out of 100) obtained by two classes, each having 80 students.
Upper limit (marks):\;10 \;20 \;30 \;40 \;50 \;60 \;70 \;80 \;90 \;100
Class A cumulative frequency: 5 \;15 \;28 \;40 \;55 \;65 \;72 \;77 \;79 \;80
Class B cumulative frequency: 8 \;18 \;30 \;47 \;60 \;68 \;73 \;76 \;79 \;80
Which class has the higher median marks and approximately by how many marks?
(a) Class B, by about 4 marks
(b) Class A, by about 9 marks
(c) Class A, by about 4 marks
(d) Both classes have nearly identical median marks (difference ≈0)