Question: #10.85: The quality control director for a clothing manufacturer wants to study the effect of machines on the breaking strength (in pounds) of wool serge material. A batch of the material is cut into square-yard pieces, and these are randomly assigned, 12 each, to the three machines chosen specifically for the experiment. The results (stored in the file Breakstw) are shown at the top of the next column:

At the 0.05 level of significance,

a) Is there an effect due to machine?

b) Plot the mean breaking strength for each machine.

c) If appropriate, use the Turkey-Kramer procedure to examine differences among machines.

d) What can you conclude about the effects of machines on breaking strength? Explain.