Suppose that a study of 1009 students shows that 70% of students who got at least 7 hours of sleep per night during a semester had a higher than average GPA (GPA > 3.25).

a. Calculate the “conservative” margin of error for this poll. Express the answer as a percent.

b. Is it more likely that this is an observational study or an experiment? Explain.

c. In this study, what variable is the explanatory variable and what variable is the response variable?

d. Which of the following variables are likely to be lurking variables in this study? Explain why in each case.

Number of courses the student took that semester

Weight of the student

Number of hours the student spent partying in a typical week