We have to relate a linear function (the regression model) with its equation.
We can see in the graph that the y-intercept, the value of y(0), is b=5.
Then, we can estimate the slope with the known points (0,5) and (2,8):
[tex]m=\frac{y_2-y_1}{x_2-x_1}=\frac{8-5}{2-0}=\frac{3}{2}=1.5[/tex]Then, with slope m=1.5 and b=5, the regression model equation should be:
[tex]y=1.5x+5[/tex]We can estimate the mood for students that spent 2.5 hours playing sports by replacing x with 2.5 in the model and calculate y:
[tex]y(2.5)=1.5\cdot2.5+5=3.75+5=8.75[/tex]NOTE: we could also have look on the graph instead of doing the calculation.
Answer: B) y=1.5x+5
The estimation of the mood for a student that spent 2.5 hours playing sports is 8.75.