SAT Two-Variable Data and Scatterplots Questions
Fitting a line to a scatterplot and reading what it predicts.
In short
- Two-Variable Data and Scatterplots is part of Problem-Solving and Data Analysis, about 15% of the scored Math questions: 5 to 7 on every test.
- Math questions from all four areas are mixed in each module and arranged from easiest to hardest.
- Line-of-best-fit prediction is the trap Rivie's practice tests set most often in Two-Variable Data and Scatterplots questions.
Common traps
Most common first, from Rivie's ten practice tests.
Line-of-best-fit prediction
Plug the given x into the line's equation to predict y; or read the y-value directly off the line at the given x. Don't average data points or pick the closest plotted point.
The usual mistake: You eyeball the data cluster and pick a value that 'looks right', missing that the question asks what the LINE predicts (which can differ from any actual data point).
Try a question
From Rivie's practice tests. Pick an answer to see why it is right or wrong.
A scatter plot's line of best fit is y = −1.5x + 20. What is the predicted y when x = 6?
Video lessons
Free on YouTube, picked for this topic.
Digital SAT Math - Ottocento #32 Scatterplots + Lines of Best Fit (FREE WKSHT)Scatterplot and best-fit lesson, then 21 questionsTutorllini Test Prep · 42 minThe only video on linear and exponential growth you need to watchLinear versus exponential growth from two pointsSAT Prep Askerra · 25 minDigital SAT Math - Desmos Lesson #21 Automatic RegressionDesmos fits a line or curve to data automaticallyTutorllini Test Prep · 6 min