SOLUTION :
CUMULATIVE FREQUENCY TABLE is in the attachment.
Here, n = 30
n/2 = 15
Since, the Cumulative frequency just greater than 15 is 19 and the corresponding class is 55 - 60 .Therefore 55 - 60 is the median class.
Here, l = 55 , f = 6, c.f = 13, h = 5
MEDIAN = l + [(n/2 - cf )/f ] ×h
= 55 + [(15 - 13)/6] × 5
= 55 +(2× 5)/6
= 55 + 10/6
= 55 + 5/3
= 55 + 1.667
= 56.667 ≈ 56.67
Hence, the Median weight of students is 56.67 kg .
MEDIAN for the GROUPED data :
For this we find the Cumulative frequency(cf) of all the classes and n/2 , where n = number of observations.
Now, find the class whose Cumulative frequency is greater than and nearest to n/2 and this class is called median class,then use the following formula calculating the median.
MEDIAN = l + [(n/2 - cf )/f ] ×h
Where,
l = lower limit of the median class
n = number of observations
cf = cumulative frequency of class interval preceding the median class
f = frequency of median class
h = class size
HOPE THIS ANSWER WILL HELP YOU.