A line of best fit follows the overall pattern of a scatterplot and gives a predicted value; each dot shows an actual measurement. When the line is already drawn, find the requested input on the horizontal axis, move to the line, and read across to the vertical axis. Don’t substitute a nearby dot for the line’s prediction.
Hints
- Hint 1
The hours of phone use are the input on the horizontal axis. Find the requested number of hours there. Which part of the graph should you move toward to get the predicted battery percentage?
- Hint 2
A dot shows one day’s measured battery percentage. The line of best fit shows the prediction, so read where the line reaches that hour, even if a dot sits nearby.
Step-by-step
Read the drawn line
Step 1Find the prediction on the line
No Desmos needed. The line to read is already drawn. Find on the horizontal axis, which measures hours of phone use. Move straight up to the line of best fit, not to the nearby dot: the question asks for the line’s prediction.
- Step 2
Read the battery percentage
From the line at , read across to the vertical axis. Its height is , and that axis measures battery percentage. So the phone is predicted to have remaining at 10 PM. Read the fitted line, not a nearby dot. Choice B.