Question 5·Medium·Two-Variable Data: Models and Scatterplots
A printing company recorded the number of posters printed and the amount of ink used (in milliliters) for several print runs. The scatterplot shown represents this relationship, and a line of best fit is also shown.
Which choice best interprets the slope of the line of best fit?
For slope-interpretation questions with a line of best fit, pick two clear points on the line, compute , then state it as “ changes by units for each 1 unit increase in ,” keeping the units tied to the context.
Hints
Look at the line, not the scattered points
To find the slope, use two clear points the line of best fit goes through.
Compute rise over run
Calculate using your two points on the line.
Attach meaning and units
A slope tells how much changes for a 1-unit increase in . Here, that’s milliliters of ink per poster.
Desmos Guide
Enter the two points from the line
In Desmos, plot the points and .
Compute the slope
In Desmos, type (48-18)/(8-2) to compute the slope.
Interpret the result
Use the slope value as “milliliters of ink per poster printed” and match it to the choice that states this rate.
Step-by-step Explanation
Choose two points on the line of best fit
From the graph, the line of best fit passes through and .
Compute the slope
The slope is
This means increases by 5 for every increase of 1 in .
Interpret the slope in context
Because is posters printed and is ink used (milliliters), a slope of 5 means the ink used increases by about 5 milliliters for each additional poster printed.