human
Interpret continuous data using a line graph ![A line graph with title "Height of rocket". 
The x-axis is titled "Time in seconds" and the scale is labelled from 0 to 90 seconds in steps of 10 seconds.
The y-axis is titled "Height in metres" and the scale is labelled from 0 to 60 in steps of 10 metres. The following points are plotted and joined together: (0, 0), (10, 10), (20, 30),(30, 40), (40, 50), (60, 60).
]() How many metres did the rocket travel between \( 20 \) and \( 50 \) seconds? \( 55 \)
gpt
When finding the difference between two points on a time series graph, only uses one of the points. 