Back to Know that straight lines are widely used to model relationships between two quantitative variables — Problem 3 · Task Set 82

Fitting Lines to Data -- Tutor Intake Assessment

This is a quick check on line-fitting concepts: when a line makes sense,
how to judge whether it fits well, and how to use a fitted line to
predict values and write its equation. The goal is to see where to focus
our first sessions together, not to grade you. Work independently,
without notes.

Grade 8·8 problems·~12 min·Common Core Math - Grade 8·container·8-sp-a-2

Work through problems with immediate feedback

Concepts

Two students each draw an informal line of best fit for the same
scatter plot. Their lines are similar in direction and position
but not identical -- one has a slightly steeper slope than the
other. Both lines follow the trend and are reasonably balanced
in the data. What should we conclude?

One of the two lines must be wrong, since there can only be one correct line of best fit

Both lines can be reasonable; informal fitting by eye does not produce one single exact answer

The steeper line is automatically the better one

The shallower line is automatically the better one