Given,

class interval                    0-10  10-20  20-30   30-40  40-50  50-60

Frequency                           5        3        10         6         4          2

Commulative Frequency:    5         8        18        24       28        30

Here, n = 30 and n/2 = 30/2 = 15

So, median class is 20-30 with commulayive frequency is 18

Now, l = 20, n = 30, cf = 8, f = 10, h = 10

Now, Median = l + (n/2 - cf)/f + h

                     = 20 + (30/2 - 8)/10 + 10      

                     = 20 + (15 - 8)/10 + 10

                     = 20 + 7/10 + 10

                     = 30 + 0.7

                     = 30.7