Building on the cup experiment of the Chapter 4 Step-By-Step, a student selects one type of container and designs an experiment to see whether the type of Liquid stored and the outside Environment affect the ability of a cup to maintain temperature. He randomly chooses an experimental condition and runs each twice:

After fitting a two-way ANOVA model, he obtains the following interaction plot, ANOVA table, and effects table:

a) State the null and alternative hypotheses.
b) Test the hypotheses at ( = 0.05.
c) Perform a residual analysis.
d) Summarize your findings.