Below is the comparison of two mutually exclusive projects.

a) Calculate payback period for both projects, and make investment decision based on payback period rule

b) Calculate NPV (net present value) for both projects, and make investment decision based on NPV

c) Calculate IRR (internal rate of return) for both projects, and make investment decision based on IRR

d) Do you have same conclusion in parts a), b) and c)? If not, which investment criteria are you going to use