Three different heat-treatment methods are being tested against four different zinc-coating techniques, with data representing the number of pounds required for a test probe to penetrate the layer of zinc coating.
Metal samples have been randomly assigned to the factor levels, with two replications in each cell. For the data shown here, use the 0.01 level of significance in drawing conclusions from this experiment.
Determine the 95% confidence interval for the population mean for each factor level.