Consider the Following to Answer the Question(s) Below

Consider the following to answer the question(s) below:
To determine whether the tip left at the end of a meal is related to the size of the total bill at their restaurant, Chez Michelle, data were gathered for 10 customers. The data and summary statistics are shown below.

-For each of the following scenarios, indicate which is the predictor variable and which is the response variable.
a. A supermarket chain gathers data on the amount they spend on promotional material (specials, coupons, etc.) and sales revenue generated each quarter.
b. Government sponsored research investigated the relationship between the number of hours individuals spend on the Internet and age.
c. A real estate association conducted a study on home prices and economic strength for different regions of Canada.