Grindwell, Inc., a manufacturer of grinding tools, is con- cerned about the durability of its products, which de- pends on the permeability of the sinter mixtures used in production. Suspecting that the carbon content might be the source of the problem, the plant manager collected the following data: Carbon Content (%) Permeability Index 5.5 16 3.0 31 4.5 21 4.8 19 4.2 16 4.7 23 5.1 20 4.4 11 3.6 20
If low permeability is desirable, what does the scatter diagram suggest with regard to the carbon content?