(Q9) The distribution below gives the weights of 30 students of a class. Find the median weight of the students.

Weight (in kg)	40-45	45-50	50-55	55-60	60-65	65-70	70-75
Number of students	2	3	8	6	6	3	2

Answer :

Class Interval	Frequency	Cumulative Frequency
40-45	2	2
45-50	3	cf 5
50-55 (l)	f 8	13
55-60	6	19
60-65	6	25
65-70	3	28
70-75	2	30

Number of observations (n) = ∑f_i

15 lies in the class 50-55

∴ Median class = 50-55

l-lower boundary of the median class =

f-frequency of the median class = 8

Class size h = 6 , c.f = 5

Median = + =

∴ Median weight = kg.