The runs scored by two teams A and B on the first 60 balls in a cricket match are given below: Represent the data of both the teams on the same graph by frequency polygons.

No. of balls Class mark Team A Team B
0.5 - 6.5 3.5 2 5
6.5 - 12.5 9.5 1 6
12.5 - 18.5 15.5 8 2
18.5 - 24.5 21.5 9 10
24.5 - 30.5 27.5 4 5
30.5 - 36.5 33.5 5 6
36.5 - 42.5 39.5 6 3
42.5 - 48.5 45.5 10 4
48.5 - 54.5 51.5 6 8
54.5 - 60.5 57.5 2 10
Class intervals are not continuous.
∴Because of gap of 1, 0.5 has to added and subtracted from upper and lower class limits.
Class mark = \frac{upper class limit + lower class limit}{2}