Back to Know that straight lines are widely used to model relationships between two quantitative variables — Problem 1 · 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

Applications

A scatter plot of 15 data points shows a positive linear
association. Line A follows the upward trend and has
roughly 7 points above it and 8 below, staying close to the
data throughout. Line B passes exactly through the two
highest data points but leaves 13 of the 15 points below it.
Which line is the better fit, and why?

Line A -- it is balanced (roughly equal points above and below) and stays close to the data overall

Line B -- it passes exactly through two real data points, which makes it more accurate

Both are equally good, since both follow the general upward direction

Neither -- a good fit requires the line to touch every data point