Class interval   Frequency
-0.9/-0.8 	 6
-0.8/-0.7 	 2
-0.7/-0.6 	 8
-0.6/-0.5 	 11
-0.5/-0.4 	 15
-0.4/-0.3 	 21
-0.3/-0.2 	 24
-0.2/-0.1 	 27
-0.1/0.0	 28
0.0/0.1		 15
0.1/0.2		 10
0.2/0.3		 6
0.3/0.4		 4
0.4/0.6		 4