Question: A fast food chain sells its burgers alone or as part of a “value meal” which includes fries and a drink. They know some customers are health conscious. They want to do an experiment to see if the proportion of customers choosing the meal would increase if they offered baby carrots with the meal as an alternative to the fries. They will compare three treatments: (1) status quo, (2) offering carrots as an alternative, but with no advertising, and (3) offering carrots as an alternative, and advertising this option in the local area.

a. What are the explanatory and response variables?

b. Diagram the experiment.