homie

""The guy above is wrong. In any case where IRR < WACC, NPV is NEGATIVE. ""

Dear Bill, IRR has nothing to do with WACC, in its calculation.

It is only after you have calculated IRR that you compare it to WACC and if it is less than WACC which means your NPV is negative. Simple artihmatics.

Ok , let me tell you from another perspective.

Take your calculator and feed Cf0=-100 and Cf1=110

Now press IRR and see what happens ? It will not be dependent on your input of I/Y button on calculator.