This scatter plot shows the association between time elapsed and distance left to go when John drove from city A to city B. What are the slope and the y-intercept of the line of best fit on the scatter plot?

Graph shows line and 6 points plotted in quadrant 1 of coordinate plane with time in minutes on X-axis and distance in miles on Y-axis. Line goes through (0, 80), (120, 5). Points are plotted at (20, 75), (40, 50), (60, 45), (80, 30), (100, 22).

1 answer

The slope of the line of best fit can be calculated using the two points that the line passes through: (0, 80) and (120, 5).

Slope = (y2 - y1) / (x2 - x1)
Slope = (5 - 80) / (120 - 0)
Slope = -75 / 120
Slope = -5/8

The y-intercept of the line of best fit can be calculated using the slope and one of the points, for example (0, 80).

y = mx + b
80 = (-5/8)(0) + b
80 = b

Therefore, the slope of the line of best fit is -5/8 and the y-intercept is 80.