Question

The following table shows the average rainfall in 150 towns. Show the information by a frequency polygon.

Average rainfall (cm)	0-20	20-40	40-60	60-80	80-100
No. of towns	14	12	36	48	40

Answer 1

Class Average rainfall (cm)	0-20	20-40	40-60	60-80	80-100	100-120
Class mark	10	30	50	70	90	110
Frequency (No. of towns)	14	12	36	48	40	0
Co-ordinate of points	(10,14)	(30,12)	(50,36)	(70,48)	(90,40)	(110,0)