7.2. Broken-Line Graphs http://www.ck12.org
Answer:
Before we write our story, let’s summarize what we know from the graph. We know that the story begins at 8:45
am, because the line touches thex-axis at the third tick mark between 8:00 am and 9:00 am. We also know that
from 8:45 am to 9:30 am, a distance of 60 km was traveled. This is because from 8:45 am to the second tick mark
between 9:00 and 10:00 am, the line goes from 0 km to 60 km on they-axis. This means that 60 km was traveled in
45 minutes, so the speed during this time can be calculated as follows:
60
45
=
x
60
45 x= 3 , 600
x=80 km/hrNext, we can see that from 9:30 am to 10:00 am, no distance was traveled, since the line is horizontal in this interval.
However, from 10:00 am to 11:00 am, 40 km was traveled, This is because from 10:00 am to 11:00 am, the line goes
from 60 km to 100 km on they-axis, and 100− 60 =40. Therefore, the speed during this time was 40 km/hr. From
11:00 am to 11:15 am, there was, again, no distance traveled, since the line is horizontal from 11:00 am to the first
tick mark between 11:00 am and 12:00 pm. Finally, from 11:15 am to 12:15 pm, 100 km was traveled, since the line
goes from 100 km to 0 km on they-axis from 11:15 am to the first tick mark after 12:00 pm. This means that the
speed during this time was 100 km/hr. Also, since the distance is decreasing in this interval, we know that this was
a return trip. Because the line touches thex-axis at 12:15 pm, this is the end of the trip.
Now we are ready to write our story. As long as it adheres to what we found above, anything is fine, but here is an
example of what we could write:
Deena is going on a shopping trip. From 8:45 am to 9:30 am, she drove her car to a neighboring town 60 km away,
traveling at a speed of 80 km/hr. She then decided to stop and have breakfast for 30 minutes before resuming her
trip. Traffic was a little heavy for the next hour, so she only managed to go 40 km in this time, traveling at a speed
of 40 km/hr. At 11:00 am, she reached the shopping mall that was her destination, but it seemed to be closed. After
looking around for 15 minutes, she decided that it was, in fact, closed, so she began her trip home. Traffic was much
lighter on the way home, so she covered the entire 100 km non-stop in 1 hour, traveling at a speed of 100 kn/hr. She
arrived home at 12:15 pm.