To predict the average final grade percentage \( y \) when a student spent 10 hours on social media (where \( x = 10 \)), we can use the equation of the trend line:
\[ y = -7.2x + 98.9 \]
Substituting \( x = 10 \) into the equation:
\[ y = -7.2(10) + 98.9 \] \[ y = -72 + 98.9 \] \[ y = 26.9 \]
Rounding to the nearest whole number, we find:
\[ y \approx 27 \]
Thus, the prediction is:
The average final grade is 27% if a student spent 10 hours on social media.