Carlos likes to bowl. He timed how long it took for his ball to travel the length of an 18-m lane in the bowling alley. He plotted the final distance and time on a line graph. Carlos drew a line from this point to the origin of the graph. A line graph A graph of distance (m) versus time (s) showing a direct relationship. The line extends from 0 to 18 meters. The line extends from 0 to 3 seconds. The point on the graph line are: (0,0); (1, 6), (2,12); (3, 18)

Use the graph to find the average speed of the ball as it moves down the lane. Explain how you found this speed.