eBook Question Content Area Payback, Net Present Value, Internal Rate of Return, Effects of Differences in Sales on Project Viability For discount factors use Exhibit 12B-1 and Exhibit 12B-2. Shaftel Ready Mix is a processor and supplier of concrete, aggregate, and rock products. The company operates in the intermountain western United States. Currently, Shaftel has 14 cement- processing plants and a labor force of more than 375 employees. With the exception of cement powder, all materials (e.g., aggregat