Question

The distribution below gives the weight of 30 students of a class.

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

Draw a ‘more than’ type ogive for the given data. Hence obtain median weight of the students from the graph and verify the result by using formula.

Answer 1

	f	cf
More than 40	2	30
More than 45	3	28
More than 50	8	25
More than 55	6	17
More than 60	6	11
More than 65	3	5
More than 70	2	2

Calculation of median by formula

Weight (in kg)	Number of students (f)	Cumulative frequency (cf)
40–45	2	2
45–50	3	5
50–55	8	13
55–60	6	19
60–65	6	25
65–70	3	28
70–75	2	30
Total	∑fi=30

The cumulative frequency just greater than n/2=15 is 19, and the corresponding class is 55 – 60.

Hence, median weight is 56.67 kg.