Exercise 8 Page 43

The graph describes the revenues generated through an online store. Observing the graph, we can see that it changes direction at four points. This creates five distinct segments which we have marked with points in the figure below.

Let's discuss what happens during each of the segments.

Segment	What's happening?
A to B	Between $A$ and $B,$ the graph points upwards, which is to say the graph is increasing. This means that revenues are increasing.
B to C	Between $B$ and $C,$ the graph points downwards, which is to say the graph is decreasing. Sales, although still positive, are now going down as time passes.
C to D	The sales have now started to increase again. We can also see that the segment is somewhat steeper, so revenues are also growing at a somewhat faster rate than before the decline between $B$ and $C.$
D to E	Between $D$ and $E,$ the graph is horizontal. This means that revenues are not zero, but they are also no growing during this time. Revenues are at a fixed level for this period.
E to F	The graph is increasing again but it's not as steep as the section between $A$ and $B$ or the section between $C$ and $D.$ This means that the revenues do not grow as fast as they did from $A$ to $B$ or from $C$ to $D.$