Which of the following two cash flow scenarios (Z1 and Z2) is better from a PW point of view, and which is better from an IRR point of view? Use a 10% per annum interest rate for the PW calculations.

Comment on why the comparison turns out the way it does. Is the slope of the curve – PW versus r – as it crosses the r axis positive or negative in each case Z1 and Z2, and what does the sign of the slope mean in terms of interpreting IRR?