Answer:
a) 
b) 





c) Figure attached
d) Figure attached
Explanation:
The proportional model on this case would be given by:

Where P is the population size, t the time on years and k a constant.
We can reorder this expression like this:

If we integrate both sides we got:

And using exponentials on both sides we got:

Where
represent the initial amount for the starting year t=0.
The rate on this case is given
, so then our model would be given by:

Part a
For this case we just need to replace t=100 and we got:

Part b
For this case we have the following:






Part c
The graph is on the first figure attached.
Part d
If we take a log-log scale we have the following values
We need to exclude the point t=0 since the natural log for 0 is not defined.
ln 1 =0 , ln 2= 0.693, ln 10=2.30, ln 25 =3.22, ln 50= 3.91
The result would be the figure 2 attached. And we see a better result for the graph.