Your teacher surveyed the class to determine the number of hours that each student spent on social media. Your teacher created a table and scatterplot graph that displayed the number of hours and the average final grade based on the hours. The trend line (equation) for the data is y=−7.2x+98.9. Interpret the y-intercept. What is the average grade if a student was on social media for 0 hours?

Answer 1

In the equation y=−7.2x+98.9, x represents the number of hours a student spent on social media and y represents the average final grade.

The y-intercept is the point where the trend line crosses the y-axis, which in this case is the value of y when x=0. So, when a student spends 0 hours on social media, the y-intercept, or the average grade is the value of y.

Using the equation y=−7.2x+98.9, when x=0:
y = -7.2(0) + 98.9
y = 98.9

Therefore, the average grade for a student who spends 0 hours on social media is 98.9.