The marks obtaine

First we’ll find the median class -

And median class is the class corresponding to cumulative frequency which is just greater than m.

Now,

And c.f just greater is 74 corresponding to 20 - 30 (median class)

Where, l = lower limit of median class, N = sum of all frequencies, C = cumulative frequency of class preceding to median class, h = size of median class, f = frequency of median class.

∴ here l = 40, N = 100, C = 32, h = 10 and f = 42.

⇒ Median = 24.28