Reconsider the Tinker Construction Co. problem presented in Prob. 10.8-1. While in college, Sean Murphy took an OR course that devoted a month to linear programming, so Sean has decided to use linear programming to analyze this problem.
(a) Consider the upper path through the project network. Formulate a two-variable linear programming model for the problem of how to minimize the cost of performing this sequence of activities within 12 months. Use the graphical method to solve this model.
(b) Repeat part (a) for the lower path through the project network.