The given data can be divided into following class intervals, as per the given directions

Class Interval Frequency Relative frequency percentage

0- 4 8 8/30=0.27 27

4- 8 9 9/30=0.3 30

8- 12 7 7/30=0.23 23

12-16 3 3/30=0.1 10

16-20 3 3/30=0.1 10

Total 30 Total=1.00