$4\mathrm{.}22.$ The effect of five different ingredients $(A,B,C,D,E)$ :

on the reaction time of a chemical process is being studied.

Each batch of new material is only large enough to permit five

runs to be made. Furthermore, each run requires approximately

$1\frac{1}{2}$ hours, so only five runs can be made in one day. The exper$-$

imenter decides to run the experiment as a Latin square so that

day and batch effects may be systematically controlled. She

obtains the data that follow. Analyze the data from this exper$-$

iment $($use $=0\mathrm{.}05)$ and draw conclusions.