Question

Timothy downloaded 10 files to his computer. The scatter plot below shows the relationship between the size of the file and the amount of time needed to download.

The graph titled Downloading files shows Time in seconds on y-axis and size in megabytes on x-axis. There are dots at (5, 30), (5, 40), (10, 37), (10, 50), (20, 50), (22, 57). (25, 75), (30, 75), (35, 87), and (37, 75).

To represent the data, Timothy drew a line through the points (0,50) and (40,75). Which statement explains why his line is not the line of best fit for the data?

A.
Most of the data points lie above Timothy’s line.

B.
Timothy’s line is more horizontal than it should be, and most of the points are too far away from the line.

C.
Timothy’s line is more vertical than it should be, and most of the points are too far away from the line.

D.
Most of the data points lie below Timothy’s line.

Answer 1

D. Most of the data points lie below Timothy’s line.

Explanation: For the 10 points, the line through (0,50) and (40,75) predicts y = 0.625x + 50. Six of the points (at smaller x) fall below that line while only four fall above it, so the line is not centered through the data and is not the best-fit line.