(part 2)

b. The x values in the data are between 65 and 75. 90 is outside the domain of the observed x values in the data (independent variable), so you cannot reliably predict the final exam score for this student. Even though it is possible to enter 90 into the equation for x and calculate a corresponding y value, the y value that you get will not be reliable.

To understand how unreliable the prediction can be outside the x values observed in the data, make the substitution x = 90 into the equation:

$ŷ=\mathrm{–173.51}+4.83\left(90\right)=261.19\text{.}$

The final exam score is predicted to be 261.19. The most points that can be awarded for the final exam are 200.