Here’s what we know:
1. C = portion
of land for corn
2. S =
portion of land for soybean
3. W =
portion of land for wheat
4. C+S+W=100%
5. 45% 
C
50%
6. 25% S
30%
7. 22.5%
W
27.5%
Now, suppose we let C=45% and S=25%, which is the lowest possible
values. Clearly this is not feasible, because W would have to equal 30%, which
is not in the allowed range for W.
Let’s try various values of C (shown in green) and S (shown in
blue), and see what value of W would be required (shown in black):
|
25% |
26% |
27% |
28% |
29% |
30% |
|
|
45% |
Not feasible |
Not feasible |
Not feasible |
27% |
26% |
25% |
|
46% |
Not feasible |
Not feasible |
27% |
26% |
25% |
24% |
|
47% |
Not feasible |
27% |
26% |
25% |
24% |
23% |
|
48% |
27% |
26% |
25% |
24% |
23% |
Not feasible |
|
49% |
26% |
25% |
24% |
23% |
Not feasible |
Not feasible |
|
50% |
25% |
24% |
23% |
Not feasible |
Not feasible |
Not feasible |
We’ve only chosen 6 values for C and S, but we can show many more
values at smaller intervals. You may want to try to replicate the above using
an Excel spreadsheet or other such program.
You can see six the corner points in the simple integer-based
table above:
However, we only looked at integer values; to be precise, we should look at all values, including fractions.
When you do this, you’ll see that the actual corner points are as follows (C,
S, W):
1. 45,
27.5, 27.5
2. 45,
30, 25
3. 47.5,
30, 22.5
4. 47.5,
25, 27.5
5. 50,
25, 25
6. 50,
27.5, 22.5