SAT MathProblem-Solving and Data AnalysisTopic Guide
SAT Scatterplot and Line of Best Fit Questions: The Five Types
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Sigma Prep
SAT Math Instructor · 10+ Years Experience
September 6, 2026·6 min read
Two-variable data is the scatterplot skill inside Problem-Solving and Data Analysis, about 15% of SAT Math. Almost every question comes with a picture, and almost every wrong answer comes from reading the picture in a hurry. The math is linear functions again: the line of best fit has a slope and an intercept, and the dots are the real data that the line is only predicting.
Predicted versus actual
The line predicts. The dot is what actually happened. Above the line means the actual value was higher than predicted, below means lower, and the vertical gap between them is the difference the questions keep asking about. Get that straight and four of the five types are reading exercises.
The five ways the SAT asks it
1. Read a value off the line
Scatterplots and models · Easyanswer C
Twelve data points are shown in the scatterplot. A line of best fit for the data is also shown. At x=1,600, which of the following is closest to the y-value predicted by the line of best fit?
Go to 1,600 on the x-axis, up to the line, across to the y-axis. Not to the nearest dot. The question says "predicted by the line of best fit," which is the line, and the answer is the closest choice to where the line sits, 15.
2. Linear or exponential, from the words
Scatterplots and models · Easyanswer B
A water tank holds 750 gallons and drains to 150 gallons at a constant rate of 60 gallons per hour. What type of function best models the relationship between the volume of water in the tank and time?
"At a constant rate" is linear. "By a constant percent" is exponential. The tank loses 60 gallons every hour, the same amount each time, so decreasing linear. When the question shows a table instead of words, check the differences: equal jumps in y mean linear, equal ratios mean exponential.
3. Actual minus predicted
Scatterplots and models · Mediumanswer C
The scatterplot below shows data for ten retail stores along with the line of best fit. For the store with the highest customer satisfaction score, which of the following is closest to the difference between the actual score and the score predicted by the line of best fit?
Find the dot they are describing, the one farthest right here, read its height, read the line's height at the same x, subtract. About 10. The wrong choices are the dot's value or the line's value on their own. The question wants the gap.
4. Count the dots on one side of the line
Scatterplots and models · Mediumanswer 6
The scatterplot shows the relationship between two variables, x and y. A line of best fit is also shown. For how many of the 10 data points does the line of best fit predict a greater y-value than the actual y-value?
"The line predicts a greater value than the actual" means the dot is below the line. Count the dots under it, carefully, dot by dot: 6. Students miss this by counting the wrong side, and the wording flips between questions, so decide which side before you count.
5. The equation of the model
Scatterplots and models · Hardanswer A
The scatterplot shows the relationship between two variables, x and y. An equation for the exponential model shown can be written as y=a(b)x, where a and b are positive constants. Which of the following is closest to the value of b?
For an exponential model y = a(b)^x, a is the y-intercept and b is the ratio between values one unit apart. The curve is falling, so b is less than 1, which rules out 1.28 and 117 immediately, and reading two points a unit apart gives about 0.78. For a linear model the same idea is slope: rise over run between two points on the line.
Try one
This is a real question from our Scatterplots · Medium set. Solve it the fast way, then watch how I do it.
try one · Scatterplots and models · Medium
In which of the following tables is the relationship between the values of x and their corresponding y-values nonlinear?
Where the points actually go
Reading the dot when the question said the line, counting the wrong side, and picking a growth factor above 1 for a curve that is falling. All three are reading, and reading gets faster with volume.
The app has 329 scatterplot and model questions, 154 easy, 105 medium and 70 hard, every one with a video explanation. The free diagnostic shows whether this is where your points are going.
Common Questions
The line is the model’s prediction; the dots are the actual measurements. A dot above the line means the actual value was higher than predicted. Questions ask for the predicted value (read the line), the actual value (read the dot), or the difference (the vertical gap).
In words: a constant amount per unit of time is linear, a constant percent is exponential. In a table: equal differences in y are linear, equal ratios are exponential. On a graph: a straight line is linear, a curve that steepens or flattens is exponential.
Pick two points that sit on the line, not on dots, and use rise over run. Read the axes carefully, since they often count by 2s, 5s or 100s. Or put the two points, say (2, 10) and (6, 22), into a Desmos table, type y1 ~ mx1 + b, and Desmos gives m = 3.
Two-variable data is one of the skills in Problem-Solving and Data Analysis, about 15% of SAT Math. Expect one or two per test, usually with a figure.
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