E ( y ) = β 0 + β 1 x 1 + β 2 x 2 + β 3 x 3

where LaTeX: yy represents exam score (0 to 100 points), LaTeX: x_1x 1 represents the amount paid to a teacher (in dollars), LaTeX: x_2x 2 represents the number of hours of sleep per week, and LaTeX: x_3x 3 represents number of study hours.

Suppose that we used a sample of 100 students to fit the following prediction equation:

y_hatLaTeX: \:=\:65\:+1.5x_1\:+\:0.2x_2\:+\:0.5 x_3= 65 + 1.5 x 1 + 0.2 x 2 + 0.5 x 3

Choose the most accurate interpretation for the slope of the amount paid to a teacher (in dollars).

Group of answer choices

a. For each additional 1.5 dollars paid to a tutor, we expect exam score to increase by 1 point, holding number of hours of sleep per week and number of study hours fixed.

b. For each additional dollar paid to a tutor, we expect exam score to increase by 1.5 points, holding number of hours of sleep per week and number of study hours fixed.

c. For each additional dollar paid to a tutor, we expect exam score to increase by 1.5 points.

d. When the amount paid to a tutor, number of hours of sleep per week, and number of study hours are set to 0, we expect an exam score of 65 points.