The rate of return determined for the incremental cash flow series or the actual cash flows can
be interpreted as a break even rate of return value.
The break even rate of return is the incremental i* value, i*, at which the PW (or AW)
value of the incremental cash flows is exactly zero. Equivalently, the break even ROR is the i
value, i*, at which the PW (or AW) values of two alternatives’ actual cash flows are exactly
equal to each other.
Break even ROR If the incremental cash fl ow ROR (i *) is greater than the MARR, the larger-investment
alternative is selected. For example, if the PW versus i graph for the incremental cash flows in
Table 8–4 (and spreadsheet Figure 8–3 ) is plotted for various interest rates, the graph shown in
Figure 8–4 is obtained. It shows the i * breakeven at 12.65%. The conclusions are that
• For MARR 12.65%, the extra investment for B is justified.
• For MARR
12.65%, the opposite is true—the extra investment in B should not be made,
and vendor A is selected.
• If MARR is exactly 12.65%, the alternatives are equally attractive.
Figure 8–5 , which is a break even graph of PW versus i for the cash flows (not incremental) of
each alternative in Example 8.3 , provides the same results. Since all net cash flows are negative