this is a market research assignment. can you please help me solve it?

At a family gathering, Dan Kessler, the manager of a local grocery store, got into a conversation with his cousin, who supervised a large number of data-entry workers at a public utility company. Kesslers cousin mentioned that his company recently had begun programming background music into the data-entry room. As a result, productivity had increased, and the number of errors had decreased. Kessler thought that playing music in a grocery store might have an impact on customers. Specifically, he thought customers might stay in the store longer if slow, easy-to-listen-to music were played. After some serious thought, he decided he should hire a marketing researcher to design an experiment to test the influence of music tempo on shopper behavior.

Questions:

1. What do you think is the independent variable and why? Be specific.
2. What dependent variables do you think might be important in the study? Name at least three.
3. What variables need to be controlled for in this experiment?
4. Using experimental design notation, design the experiment. What design is most appropriate in this situation? Explain.