Grindwell, Inc, a manufacturer of grinding tools, is concerned about the durability of its products, which depends 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

a. Draw a scatter diagram for these data.

b. Is there a relationship between permeability and carbon content?

c. If low permeability is desirable, what does the scatter diagram suggest with regard to the carbon content?