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In Depth Information

Exhibit 9.2
Spreadsheet structure for solver

Value of the maximum Z. . . . . $ 5,480,970.34

Total Projects selected . . . . 98.7.

The solution resulted in fractional values for project types 1, 2, and 4. How we

deal with this situation depends on how strongly we feel that the constraints must

be strictly maintained. For example, we could simply round every variable in the

solution
up
to the next highest value:
X
1
=

3. Rounding these

fractional values
up
will require more resource hours. This will violate our con-

straints, but may or may not create a problem for YRA. To determine the effect on

the use of resource hours, insert these values into the worksheet area containing the

values of the decision variables, D2:D8.

It is easy to assume a
false-precision
when devising the constraints of a formu-

lation. The constant values of the
right-hand side
of the constraints (which we call

RHS) may simply be estimates. For example, the RHS of the Res-A hours con-

straint, 800, could be 812 or 789. So there may be some latitude in our ability to

deal with fractional results. Conversely, if the constraints are
hard and fast
,asolu-

tion could be implemented that rounds all, or some, of the fractional values
down

to insure strict adherence to the constraints. YRA should have an understanding of

the precision of the data used in the formulation, and they will have to decide how

to deal with this issue. Regardless, they have available the formulation to test the

6;
X
2
=

20;
X
4
=

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