A line of best fit shows the trend through the dots on a scatterplot. If a question asks for a prediction based on the line, find the given input on the horizontal axis, move up to the line, and read the score on the vertical axis. A dot at the same input shows an actual result, which may differ from the prediction.
Hints
- Hint 1
Each dot is an observed score, meaning one student’s actual result. The prediction comes from the line of best fit, even if there’s a dot at the requested number of books.
- Hint 2
Find 8 books on the horizontal axis. Move straight up to the line, not the dot, then look left to estimate the score on the vertical axis.
Step-by-step
Read the prediction from the line
Step 1Choose the line instead of the dot
No Desmos needed. Read the answer off the line of best fit. The dot at is an observed score: one student’s actual result. The question asks what the line of best fit predicts. For a prediction, read the line, not the dot.
- Step 2
Read the score at 8 books
Find on the Books read axis and move straight up to the solid line. Then look left to the Test score axis. The line is a little below , at about , so the predicted vocabulary test score is . Choice C.