Question 8.5: Equivalence of Real-Dollar and Actual-Dollar Cash Flows In E...
Equivalence of Real-Dollar and Actual-Dollar Cash Flows
In Example 8-1, your salary was projected to increase at the rate of 4% per year, and the general price inflation rate was expected to be 6% per year. Your resulting estimated salary for the four years in actual and real dollars was as follows :
End of Year, k | Salary (A$) | Salary (R$), b = 1 |
1 | 45,000 | 45,000 |
2 | 46,800 | 44,151 |
3 | 48,672 | 43,318 |
4 | 50,619 | 42,500 |
What is the present worth (PW) of the four-year actual- and real-dollar salary cash flows at the end of year one (base year) if your personal MARR_{m} is 10% per year (i_{m})?
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(a) Actual-dollar salary cash flow:
PW(10%)1 = $45,000 + $46,800(P/F, 10%, 1)
+ $48,672(P/F, 10%, 2) + $50,619(P/F, 10%, 3)
= $165,798.
(b) Real-dollar salary cash flow:
i_{r}=\frac{i_{m}-f}{1+f}= \frac{0.10 − 0.06}{1.06}= 0.03774, or 3.774%;
PW(3.774%)_{1} = $45,000 + $44,151 \left(\frac{1}{1.03774} \right)^{1} + $43,318\left(\frac{1}{1.03774} \right)^{2} + $42,500 \left(\frac{1}{1.03774} \right)^{3}
= $165,798.
Thus, we obtain the same PW at the end of year one (the base time period) for both the actual-dollar and real-dollar four-year salary cash flows when the appropriate interest rate is used for the equivalence calculations.