A hot air balloon takes off and ascends at a constant rate. Once it reaches a certain elevation, it stays at the same elevation, or its cruising altitude, for some time. Then, it continues ascending at a constant rate.
This graph shows a hot air balloon's elevation in meters as a function of time in minutes. What was the hot air balloon's elevation when it was at its cruising altitude? In other words, what was the hot air balloon's elevation when its elevation was not changing?
x
y
0
1
2
3
4
5
6
7
8
9
10
11
0
60
120
180
240
300
360
420
480
540
600
Time (minutes)
Elevation (meters)
The hot air balloon was at an elevation of
meters when it was at its cruising altitude.
Nice!
What is the slope of this highlighted line segment?
x
y
0
1
2
3
4
5
6
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10
11
0
60
120
180
240
300
360
420
480
540
600
Time (minutes)
Elevation (meters)
The slope is
.