What decision criterion should be used to choose investment projects for a firm with unlimited funds available at a weighted-average cost of 10 percent (after tax)? Can the firm use the same decision...

What decision criterion should be used to choose investment projects for a firm with unlimited funds available at a weighted-average cost of 10 percent (after tax)? Can the firm use the same decision criterion if it has only a limited amount of available funds, say $100 million? Explain.