is the graph a straight line or exponential?
http://img41.imageshack.us/i/26261347.jpg/
As you can see, there are three parts marked by the dotted lines
for you to draw the graph within.
The 1st part of the Graph, namely the part which is at the most
bottom and below all the dotted lines, you will have to draw it
exponentially.
The 2nd part will be a straight line continuing from the first
part.
The 3rd part will also be a straight line, but it will be even
more steeper than the 2nd part.
The reason is that the bottom part of the container has a
decreasing 'waist' size, hence the rate at which the height
increases will get faster and faster, hence the exponential
graph.
The 'waist' size at the 2nd part is constant, hence the straight
line continuing from the 1st part.
The 'waist' size at the 3rd part is also constant, but much
smaller than that of the 2nd part, thus the sudden change in the
steepness of the line.