4. The Scampini Supplies Company recently purchased a new delivery truck. The new truck costs $22,500, and it is expected to generate after-tax cash flows, including depreciation, of $6,250 per year. The truck has a 5 -year expected life. The expected year-end abandonment values (salvage values after tax adjustments) for the truck are given here. The company's WACC is 10%. Should the firm operate the truck until the end of its 5-year physical life; if not, what is the truck's optimal economic life