To predict the average final grade percentage (y) for a student who spent 10 hours on social media (x), you can substitute x = 10 into the equation of the trend line:
\[ y = -7.2x + 98.9 \]
Substituting \( x = 10 \):
\[ y = -7.2(10) + 98.9 \]
\[ y = -72 + 98.9 \]
\[ y = 26.9 \]
Rounding to the nearest whole number, the average final grade percentage is approximately 27%.
So, the correct response is:
The average final grade is 27% if a student spent 10 hours on social media.