The first four questions are true and false

1. In order to tell the impact of a change in a constraint coefficient, the change must be made and then the model resolved.

2. Any change to the objective function coefficient of a variable that is positive in the optimal solution will change the optimal solution.

3.  A marketing research firm must determine how many daytime interviews (D) and evening interviews (E) to conduct. At least 40% of the interviews must be in the evening. A correct modeling of this constraint is: -0.4D + 0.6E > 0.

4. Alternative optimal solutions occur when there is no feasible solution to the problem.