constuct a frequency polygon for given data:

Class interval frequency

0-4 5

5-9 8

10-14 12

15-19 9

20-24 4

First make the above data as continuos one

Class interval frequency
-0.5-4.5 5
4.5-9.5 8
9.5-14.5 12
14.5-19.5 9
19.5-24.5 4

For each find the class marks i.e mean of lower and upper limit
It will be as follows
2.
7
12.
17
22

Plot line graph using class marks and corresponding frequency to get frequency polygon