Here is a (draft of a) project I am doing for
a Microeconomics class at Empire State College.
Here is the project:
If the application doesn't come up
you will probably need the Java Plug-in.
This is available (free) from Sun
Click on the appropriate download link under the "JRE"
column. This will get you to the correct
This page works with Microsoft Internet Explorer.
If you are using Netscape Navigator,
then click here.
Sometimes it appears to be taking a while to load.
If you move the mouse over the blank area of the
screen (between the two horizontal rules) it may
speed things up a bit, but I have no idea why.
There can be problems with the graph display.
If the graphs don't look right, hit the
"Update" button, which should
fix the problem.
- TC - Total Cost
- TR - Total Revenue (= Q * P, both from the demand curve)
- profit = TC - TR
- AC - Average Cost (= TC / Q)
- MC - Marginal Cost (= ΔTC / ΔQ)
- MR - Marginal Revenue (= ΔTR / ΔQ)
- AR - Average Revenue (= TR / Q)
There are two variables which can be changed:
This is the slope of the demand curve,
which is displayed as the AR,
except when the slope is zero,
when the AR is the same as the MR.
The slope must be a valid (floating point)
and must be less than zero.
For a non-zero slope (a price maker), the intercept
is the place the demand curve will cross the
"Quantity" (x-axis) line.
An increase in the intercept will shift the
demand curve to the right.
However, for a zero slope (a price taker), the
demand curve doesn't cross the x axis, so
in this case, it will be the y intercept, or price.
May I suggest that for a zero slope, a low price (perhaps
around 15) might be more appropriate, since
the graphs do not adjust their scales
The intercept must be a valid (floating point)
The "Update" Button
Clicking the "Update" Button causes both
graphs to be re-drawn. This is very quick.
It can be used after slope or intercept is updated,
or any time that the graph(s) are not properly
The Graph Scale
Please note that the "scale" of the
graphs will change as values are changed.
Both graphs will use the same "x"
value, but it may change as the slope or intercept
Each graph has its own value for the "y"
scale. Again, they will change as the inputs change.
Note that this is not a particularly sophisticated
"dynamic scale", but it works pretty well
for most "reasonable" values.