profibility index = PV of future cah flows / initial investments
Net present value = The difference between an investment market value and its cost is called the NPV.
When cash inflows are even:
NPV = R × 1 − (1 + i)-n − Initial Investment
i
R= is the net cash inflow expected to be received each period;
i=is the required rate of return per period;
n =are the number of periods during which the project is expected to operate and generate cash inflows.