Question 16·Easy·Two-Variable Data: Models and Scatterplots
The scatterplot shows the relationship between the number of hours a smartphone is used in a day, , and the battery percentage remaining at 10 PM that day, . A line of best fit is shown.
According to the line of best fit, approximately what battery percentage is expected to remain at 10 PM if the phone is used for hours in a day?
For prediction questions with a scatterplot model, treat the line of best fit as the model: start at the given -value, move to the line, then read the corresponding -value using the axis scale (not individual data points).
Hints
Use the model line
Because this is a prediction question, use the line of best fit rather than any individual plotted point.
Go to first
Find on the x-axis and move straight up to the line of best fit.
Then read the y-value
From the line, move straight across to estimate the battery percentage on the y-axis.
Desmos Guide
Enter two points on the best-fit line
From the graph, the line of best fit passes through approximately and . Enter these points in Desmos.
Write the line through the points
Compute the slope:
Using , the line is . Enter in Desmos.
Evaluate the model at
Compute to get the predicted battery percentage at , which matches the correct choice .
Step-by-step Explanation
Use the line of best fit at
On the graph, locate on the x-axis and move vertically until you reach the line of best fit.
Read the corresponding y-value
From the point where meets the line, read horizontally to the y-axis. The value is about , so the predicted battery remaining is .