In general how would each of the following factors affect the investment decision and how should each be treated 1. The expected life of the existing machine decreases. 2. the WACC is not constan?

If the expected life of the existing machine decreases, it may prompt a reevaluation of the investment decision, as shorter lifespans can lead to increased depreciation and reduced returns. This should be treated as a risk factor, potentially leading to a more conservative approach in evaluating new investments or replacement options.

If the Weighted Average Cost of Capital (WACC) is not constant, it implies fluctuating costs of financing that can affect the net present value (NPV) and overall attractiveness of an investment. This variability should be factored into the investment analysis, possibly requiring sensitivity analysis to assess how changes in WACC impact projected returns.