A manufacturer of bathtub enclosures produces a plastic polymer as a base compound and reinforces it with a filler to achieve strength. The fillers are supplied by one of two vendors, Polyfiber and Neptune Plastics. Some of the plant technicians have claimed that Polyfiber produces better filler than Neptune Plastics. A preliminary test is set up as follows: Six batches of the plastic polymer are separated in sub batches and either mixed with Polyfiber or Neptune Plastics filler. Test specimens measuring 4" x 4" are subjected to a standard breaking strength test that measures the force required to break through a particular test specimen.

The results were as follows in the table below.

• Do these data show with statistical significance that Polyfiber is a better filler than Neptune Plastics? Use any you think is appropriate.

Batch	Polyfiber	Neptune Plastics
1	1045	1015
2	1215	1005
3	1207	990
4	930	966
5	960	940
6	1060	920