Text book: Michael C. Ehrhardt (2017). Corporate finance (6th edition). Boston:CengageL. When appraising mutually exclusive investments in plant and equipment, financial managers calculate the investments’ equivalent annual costs and rank the investments

Text book: Michael C. Ehrhardt (2017). Corporate finance (6th edition). Boston:CengageL. When appraising mutually exclusive investments in plant and equipment, financial managers calculate the investments’ equivalent annual costs and rank the investments on this basis. Why is this necessary? Why not just compare the investments’ NPVs? Explain.