3.19 The yield of a particular chemical reaction depends on the temperature at which the reaction is carried out. The investigators are interested in comparing the yield at temperatures 100°F, 150°F, and 200°F. They can conduct a reaction 12 times in an 8-hour shift.

a Identify the response variable.

b Identify treatments.

c Design a completely randomized experiment to compare yield at different temperatures.

d How many replications of each treatment are possible in an 8-hour shift?