Question

The marks obtained by 120 students in a test are given below:

Marks	0 - 10	10 - 20	20 - 30	30 - 40	40 - 50	50 - 60	60 - 70	70 - 80	80 - 90	90 - 100
No. of Students	5	9	16	22	26	18	11	6	4	3

Draw an ogive for the given distribution on a graph sheet.
Use suitable scale for ogive to estimate the following :
(i) the median.
(ii) The number of students who obtained more than 75% marks in the test.

Answer 1

Marks C.I.	No. of Students f	C.F.
0 - 10	5	5
10 - 20	9	14
20 - 30	16	30
30 - 40	22	52
40 - 50	26	78
50 - 60	18	96
60 - 70	11	107
70 - 80	6	113
80 - 90	4	117
90 - 100	3	120

(i) Here n = 120, even
∴ Median = `(120/2)^"th"` observation
= 60^th observation
= 42·5 (approx)

(ii) Number of students who obtained more than 75% marks in the test = 120 - 110 = 10
(iii) Number of students who did not pass the test if minimum marks required to pass is 40 = 52.