(24 total points) An experiment was conducted to aid in developing a product that can be used as a substrate for making 36 ribbons. The experiment was designed to investigate the effects of base polymer and additive on the tensile strength of the resulting ribbon. There are two factors of interest: (1) base polymer: Mylar, nylon and polyethylene and (2) additive: c1, c2, c3 and c4. Use the ribbon data file posted on Canvas to do an appropriate analysis.

(3 points) Write out the three null hypotheses to be tested in words.

(3 points) Write out the appropriate statistical model and explain all terms.

(4 points) Construct an interaction plot where additive is the trace factor. Based on the plot, does there appear to be evidence of an interaction? Hint: Since there are 4 different additives, youll have to modify the following arguments for the code in R for the interaction plot to ensure that all 4 levels of the additive are plotted. Note that you can use any number in the pch argument and any colors in the col argument.

The code here is for two levels:

pch=c(1,2), col = c("red", "blue")

The code here is for three levels:

pch=c(1,2,3), col = c("red", "blue", green)

What can you do for four levels?