Answer:
a. 3
Step-by-step explanation:
An independent variable is the variable that is changed in an experiment to test its effects on the dependent variable. i.e. inputs
A dependent variable is the variable being tested, measured or predicted in an experiment. I.e a outcome
In this case, the the effects of the amount tutors are paid a week before exam, the amount of sleep before exam and the number of study hours are input variables to determine or predict a students score in exam
The independent variables are;
x1 =represents the amount paid to a tutor (in dollars) in the week before the exam
x2 = represents the number of hours of sleep in the week before the exam
x3 = number of study hours in the week before the exam
The dependent variable is the exam score
B0, B1, B2,B3, B4 are coefficients