An experiment was conducted to investigate heat loss for a coating placed on commercial thermal panes. There were five thicknesses of the coating applied to the panes: 0 (Control), 20, 40, 60, and 80 units. Ten panes were randomly assigned to each of the thicknesses. The interior temperature during the test period was set at 70?F and the average heat loss through the pane was recorded over a range of exterior temperatures. The heat loss data is given in the following table:

Thickness Heat Loss Data 10.2 10.8 10.1 10.9 11.1 11.8 11.3 11.9 9.3 9.9 20 9.2 9.8 9.1 9.9 10.1 10.8 10.3 10.9 9.3 9.8 40 9.0 9.9 9.2 9.8 10.0 10.8 10.2 10.7 9.9 9.0 60 8.1 8.1 8.0 8.9 8.2 8.9 8.1 8.8 9.2 9.9 80 7.2 7.8 7.1 7.9 8.1 8.8 8.3 8.9 9.3 9.8