SAT Math: Use a line or curve of best fit to make predictions
23+ practice questions in Praczo
The concept, explained
- 1
To predict a y-value for a given x, plug x into the model equation or read the line/curve at that x.
- 2
Only trust predictions within the range of the data (interpolation). Extrapolating far beyond is risky — the model may not hold.
- 3
Rounded or approximate predictions are expected when reading from a graph. Match the answer's precision to the graph's precision.
- 4
If the model is a line of best fit y = mx + b, prediction is just arithmetic: plug in and solve.
- ✗ Confusing the x and y in the model equation.
- ✗ Reading off an actual data point rather than the predicted value on the fit line.
SAT-style practice
The line of best fit for a scatterplot is y = 2.5x + 40. Using the model, what is the predicted y-value when x = 20?
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