a$.$ Develop and solve an integer programming model for maximizing the net present

value.

b$.$ Assume that only one of the warehouse expansion projects can be implemented. Mod$-$

ify your model of part $($a$).$

c$.$ Suppose that, if test marketing of the new product is carried out, the advertising cam$-$

paign also must be conducted. Modify your formulation of part $($b$)$ to reflect this new

situation.