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3.7 / Notation and Cash Flow Diagrams /Tables 75
A= $2524
_|
2 3 4=N
= 10% per year FIGURE 3-3
Cash Flow Diagram for Plan 3
of Table 3-1 (Lender's Viewpoint)
P= $8,000
The cash flow diagram employs several conventions:
The horizontal line is a time scale, with progression of time moving from left to
right. The period (e.g., year, quarter, month) labels can be applied to intervals
of time rather than to points on the time scale. Note, for example, that the end of
Period 2 is coincident with the beginning of Period 3. When the end-of-period
cash flow convention is used, period numbers are placed at the end of each time
interval as illustrated in Figures 3-2 and 3-3.
The arrows signify cash flows and are placed at the end of the period. If a
distinction needs to be made, downward arrows represent expenses (negative
cast flows or cash outflows) and upward arrows represent receipts (positive
cash Hows or cash inflows).
3. The.cash How diagram is dependent on the point of view. For example, the
Situations shown in Figures 3-2 and 4-4 were based on cash flow as seen by the
‘ender. If the directions of all arrows had been reversed, the problem would
have been diagramme: the borrower's viewpoint.
7 EXAMPLE 3-1
Before evaluating the economic merits of a proposed investment, the XYZ Corpo- |
ration insists that its engineers develop a cash flow diagram of the proposal. An |
investment of $10,000 can be made that will produce uniform annual revenue of | | ¥
$5,310 for five years and then have a market (recovery) value of $2,0( df
of year five. Annual expenses wil 000 at the end of each year for operating |
and maintaining the project. Draw a cash flow diagram for the five-year life of the
projéct. Use the corporation’s viewpoint.
SOLUTION
As shown in Figure 3-4, the initial investment of $10,000 and annual expenses of
$3,000 are cash outflows, while annual revenues and the market value are cash
inflows.
Notice that the beginning of a given year is the end of the preceding year. For
example, the beginning of year two is the end of year one.
Example 3-2 presents a situation in which cash flows are represented in tabular
form to facilitate the analysis of plans/designs.
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76
FIGURE 3.4
CHAPTER 3 / MoNey~Time RELATIONSHIPS AND EQUIVALENCE
$5310 $5310 $5,310 $5310 $5310
$3,000 $3,000 $3,000 $3,000 $3,600
Years
10,000
Cash Flow Diagram for Example 3-1
EXAMPLE 3-2
In a company's renovation of a small
office building, two feasible alternatives
{ot upgrading the heating, ventilation, and air conditioning (HVAC) system have
been identified. Bither Alternative A or Altemative B muse be implemented. The
costs are ‘
Alternative A Rebuild (overhaul) the existing HVAC system
+ Equipment, labor, and materials to upgrade... $18,000
+ Annual cost of electricity... vores 32,000
* Annual maintenance expenses...
eee 100
Alternative B_ Install a new HVAC system that utilizes existing ductwork
* Equipment, labor, and materials to install. 560,000
* Annual cost of electricity... 9,000
* Annual maintenance expenses. : E 16,000
* Replacement of a major component 4 years hence. 9400
Atthe end of eight ‘Years, the estimated market value for Alternative A is $2,000,
and for Alternative B it is $8,000. Assur
me that both alternatives will provide
mapharable service (comfort) over an eightsyear time period, and assume that the
major component teplaced in. Alternative B will have no market value at the end of
Year eight. (1) Use a cash flow table and end-of-year convention to tabulate the ret
£28h flows for both alternatives. 2) Determine ae annual n
between the alternatives (l
‘et cash flow difference
B~ A). (3) Compute the cumul
the end of year eight. (Th
lative difference through
© cumulative difference is the sum of differences, B - A,
from year zero through year eight)
Soturion
The cash flow table (company’s viewpoint) for this exai
imple is shown in Table 3-2
Based on these results, several points can be made (1) doing nothing is not an
option—either A or B must be selected; (2) even though positive and negative cash
flows are included in the table, on balance we are investigating two “cost-only”
alternatives; (3) a decision between the two alternatives can be made just as easily
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native A Alternative B Difference cr
astcash FLOW Net Cash Flow (BA) me
$ 18,000 60,000 12000
=" 34400 25,000 32,600
= hoo ~ 25,000 9,400 = B20)
= 34400 - 25,000 9,400 = 13,800
= 34400 = 25,000 - 9,400 0 ~ 13,800
= Hho - 25,000 9400 ~ 4400
= 3400 — 2,000 9400 5,000
= 400 = 25,000 9400 14400
= 3400 + 2,000 25,000-+ 8,000 15,400 29,800
$291,200 $261,400
IZ2235 is5
on the difirence in cashflows (i, 0” the avoidable difference) as it can on the
ae tone net cash flows for Alternatives A and B; (4) Alternative B has cash
flows identical to those of Alternative A except for the differences shown in the
table, so if the avoidable difference can “pay its own way,” Alternative B is the
verotamended choice; (6) cash flow changes caused by inflation or other suspected
Fnfluences could have easily been inserted into the table and included in the
analysis; and (6) it takes six years for the extra $42,000 investment in Alternative B
to generate sufficient cumulative savings in annual expenses to justify the higher
investment (this ignores the time value of money). So, which. alternative is better?
Weill be able to answer this question later when we consider the time value of
money in order to recommend choices between alternatives. hs
It should be apparent that a cash flow table clarifies the timing 6f cash flows,
the assumptions that are being made, and the data that are available. A cash flow
table is often useful when the complexity of a situation makes it difficult to show
all cash flow amounts on a diagram.
xl
Jopment and illustration
assessing the economic
les 3-1 and 3-2
, The remainder of Chapter 3 deals with the devel
of equivalence (time value of money) principles for
activeness of investments such as those proposed in Examp]
Tae
‘ewpoint: In most examples presented in this chapter, the company’s investor's)
e
“ewpoint will be taken 2 ginba Bead Lip,
7 D>
i
Interest Formul oo :
las Relating P1 it
setergegmaiea ater So
lows ~
Oy SCRBL
Figure 3.5 2
a future coe cash flow diagram involving-a presént Sing é am,
im, F, separated by N periods with interest at *% per period.
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7s cnapren 3. J) Movey=Te ReLarisuPs ano Eouv
F = Future Equivalent Fing
1 1
je Interest Rate per Period
FIGURE 3-5
General Cash Flow Diagram
Relating Present Equivalent
and Future Equivalent of
Single Payments
int (Given)
p = Present Equivale
shown in Figure 3-5, indicates
lashed arrow, such as that shown 3 .
re ned ‘Taro formulas relating a given P and its unknoyin
3-2and 33.
‘Throughout this chay
the quantity to be det
equivalent F are provided in Equations
Finding F When Given P .
dollars is invested at a point in time and ; % is the interest
; ; il] grow to a future amount of
th) rate per period, the amount will gi )
(prof or grote a Pepi y teen of two periods the amour i
grow to P(1 +i)(1 +1) (1 +i); by the end of three pet ods, the amount will grow
TPC + ae(1 +i) = P+ and by theend of N periods the am:
F=pa+i (32)
If an amount of P
EXAMPLE 3-3
Suppose that you borrow $8,000 now, promising to repay the loan principal plus
SUPP ost ated interest in four years at i = 10% per year. How much would you
repay at the end of four years?
SOLUTION
‘Amount Owed Interest Owed ‘Amount Owed Total End-of-
Year___at Start of Year for Each Year atEnd of Year___Year Payment
1 P = $8000 iP =$ 800 PU+i) =$ 8800 0
2 Pati =$8800 iP +i) 880 P+i =$ 9,680 0
3 PUFF = $9,680 iPU+I =$ 968 PL +i) = $10,648 0
4 P+)? = $10,648 PCL +i) = $1,065 POL +i)* = $1,713 F = $11,713
In general, we see that F = P(1 +)", and the total amount to be repaid is
$11,713. This further illustrates Plan 4 in Table 3-1 in terms of notation that we
shall be using throughout this book.
The quantity (1 + i) in Equation 3-2 is commonly called the single paymen!
compoun ar. Numerical values for this factor are given in the second
column from the left in the tables of Appendix C for a wide range of values of!
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\d Ful
present an ;
plating
38!
11 use the functional symbol (F/P, %,N)
pook we shal nantewy
oe ton oe can be expressed 3
ence E F = P(F/P,i%,N) oo
ventheses i oad “find F given P at Me interest per
is Bae ot Eatin 5.3, where the unknown quantity, F,is placed onthe
ihe initial Fa Of the equation. ‘This sequencing of letters is true of all functional
jeft-hand 5 in this book and makes them easy to remember.
sybase eof Binding F when given P, together with a cash flow diagram
Another x ein Table33. Noten Tablet for each ofthe six common
and solution Tfand interest circumstances covered, two problem statements are
discrete com: fogy and (b) in equivalence terminology —but
rm orvaing-ending ter
) ation. Indeed, there are generally many
Jepresentthesame cas love situ
rer given cash flow situation can be expressed.
an agood way to interpret a relationship such as Equation 3-3 is that
thecalculated amount, F, at the point in time at which it occurs, is equionlent to (i.e,
can be traded for) the known value, P, at the point in time at which it occurs, for
the given interest or profit rate i.
iven—(@)
they both
ways in W
In genet
Finding P When Given F
3-2, F = P(1 + i)
1
P= (45) =Fa+i® (3-4)
‘The quantity (1 4-1)" is called the single payment present worth factor. Numerical
fhe third column of the tables in Appendix C for
Values for this factor are given in #
wide range of values of 'and N. We shall use the functional symbol (P/F, i%,N)
for this factor. Hence
From Equation N, Solving this for P gives the relationship
P = F(P/F, i%,N) (5)
EXAMPLE 3-4
\/ | An investor owner) has an option to purchase a tract of land that will Be worth
each year, how much
$10,000 in six years. If the value of the land ii %
: “ars. I increases at 8%
should the investor be willing to pay now for this property?
SOLUTION
The purchase pri :
rchase price can be determined .
Reece aie letermined from Equation 3-5 ai
nd Table C-11 in
P = $10,000(P/F, 8%, 6)
P = $10,000(0.6302)
= $6,302
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Chap,
ER
1
Money—Te Retarowsues ano EOUVALENSE
Another example of this type of problem, together with a cash flow diagran,
and "
Solution, is given in Table 3-3-
39 Inter ang a Uniform
Se est Formulas Relating 4 | and
Fut ies (Annuity) to Its Present
‘ure Equivalent Values
nvolvi jes of uniform
Figure 3-6 showsa general cash flow digit” valving peri ay
teceipts, each of amour! & Seeeee end of 220 Fried an annuity, tt sho A
interest at M% per period. Such uniform reais often etch hou i“
be noted that the formulas and tables to be presen|
occurs at the end of each period, an‘ thus: ;
+ period before the fi
1. P (present equivalent value) occurs one interest period eto! first A
iform mount). . elast A, dN .
2 yar equivalent value) occurs at the same time aS the last A, and N periods
fter P. a.
3. A (annual equivalent value) occurs at the end of periods | through N, inclu.
sive.
“The timing relationship for P,A,and F ean be observed in Figur’ 3-6. Four formulas
relating A to F and P will be developed,
» 3.9.1. Finding F When Given A
at the end of each period for
the amount of A dollars occurs ‘
is the interest (profit or growth) rate per period, the future
nd of the Nth period is ‘obtained by summing the
he cash flows. Thus,
i%,N — 2) + A(E/P, i%,N -—3)+°
Ifa cash flow i
N periods and
equivalent value, F, at the ©
feture equivalents of each of t
f= A(E/P,i%,N ~ 1) + AE/P,
“+ A(E/P,i%, 1) + AE/P, 1%, 0)
rea+)h 240+)
Wo pee t+) +I
= Al( +)
‘A= Uniform Amounts (Given)
jf i it i
! 1 2 3 N-1 | N=Number
' Period | of Interest
' | Periods
t i= Interest Rate per Period ‘ .
1
P= Present Equival
resent Equivalent (Find) F = Future Equivalent (Find)
FIGURE 3-6 General Cash Flow Diagram Relatit if
ing Uniform Series (Ordinary Annu
Present Equivalent and Future Equivalent Values aaa raree
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ty) to Its Present and Future E
iform Series (Annu ‘quivalent
peiating 2 UN Values, es
erms eometric sequence f
- pracketed terms comprise @ quence havin
is ry Recall that the sum of the first N terms (5.) of a go
8 8 common ratio of
‘Ometric sequence is
(#1)
ay isthe frst term in the sequence, a» is the last term, and bis the com,
mon
where " si
see welet b= (11a = 1+ 9"% and ay = (1+ 2°, then
14
(1+i%) -
(+a
FrA i
a5
which reduces to
(1+ i%-1
Fe {een (3-6)
The quantity {[(0 + — 1]/i} is called the uniform series compound amount factor,
Tris the starting point for developing the remaining three uniform series interest
factors,
Numerical values for the uniform series compound amount factor are given in
the fourth column of the tables in Appendix C for a wide range of values of i and
N. We shall use the functional symbol (F/A, i%, N) for this factor. Hence Equation
3-6 can be expressed as
F = A(F/A,i%,N) (3-7)
Examples of this type of “wealth accumulation” problem based on the (F/A, i%,
N) factor are provided here and in Table 3-3.
EXAMPLE 3-5
{@) Suppose you make 15 equal annual deposits of $1,000 each into a bank account
Paving 5% interest per year. The first deposit will be made one year from today.
ow much money can be withdrawn from this bank account immediately after
the 15th deposit?
SoLurion
merits of A 's $1,000, N equals 15 years, and i = 5% per year. Immediately
Payment, the future equivalent amount is
F = $1,000(F/4,5%, 15)
= $1,000(21.5786)
= $21,578.60
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3.9.2
QUVALENCE
‘omapten 3 / Money—Tue Rearinsns 0 E
coincident with
Notice in the cash flow diagram below that the value of F is ¢ he
in the cash flow
last payment of $1,000.
ae?
End of Year (OY)
(b) ‘oillustrate further the amazing effects of compound ee coi he
7 ani for
lity of this statement: age an
meer Ba Ife, you can become a millionaire.” Lets assume you live to age
BD and the annual interest rate is 10% (i = 10%) Under these specific conditions,
wre compute the future compound amount (F)t0 be
F = $365/yr. (F/A, 10%, 60 years)
= $365 (3,034.81)
= $1,107,706 .
sumptions given! The moral isto start saving |
‘Thus, the statement is true for the ass
ding work on your behalf!
early and let the “magic” of compoun‘
ney early and preserving resources through
frugality avoiding waste) are extremely important ingredients of veal cretion
in general. Often, being frugal means postponing the satisfaction of immediate
material wants for the creation of a better tomorow. In this regard, be very
cautious about spending tomorrow's cash today by undisciplined borrowing (e.g.
with credit cards). The (F/A, i%, N) factor demonstrates how fast your debt can
accumulate!
A feco words to the wise: Saving mo
Finding P When Given A
From Equation 3-2, F = P(1+i)". Substituting for F in Equation 3-6, one determines
that
Pa +i = ajar]
i
Dividing both sides by (1+,
= (+aN-1
u Ae : oS
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4g | Relating @ Uniform series ( t Values i
‘on 38s the relation for finding the present equival
the beginning of the first period) of a uniform series of chloe bs of
toe peeint for N periods. The quantity in brackets is called the unyjorn con®
act wort aor. Numerical vals for this factor are given in he fh column
rhe tables in Appendix C fora wide range of values of i and N. We shall earn
functional symbol (P/A,i%, N) for this factor. Hence e the
P = A(P/A,i%,N) (09)
Thus, Equati
EXAMPLE 3-6
Ifa certain machine undergoes a major overhaul now, its output can be increased
by 20%-—which translates into additional cash flow of $20,000 atthe end of each
year for five years. If | = 15% per year, how much can we afford to invest to
overhaul this machine?
SOLUTION
The increase in cash flow is $20,000 per year, and it continues for five years at 15%
annual interest. The upper limit on what we can afford to spend is
P = $20,000(P/A, 15%, 5) te
= $20,000(3.3522) h a
= $67,044 Rx
5
yO -
EXAMPLE 3-7
Suppose that your rich uncle fias $1,000,000 that he wishes to distribute to his heirs
at the rate of $100,000 per year. If the $1,000,000 is deposited in a bank account
that earns 6% interest per year, how many years will it take to completely deplete
the account? How long will it take if the account earns 8% interest per year instead
of 6%?
ce
SOLUTION
From Table C-9, solve for N in the following equation: $1,000,000 = $100,000(P/A,
6%,N); N = 15.7 years. When the interest rate is increased to 8% per year, it will
take 20.9 years to bring the account balance to zero, which is found by solving this | yy
equation: 10 = (P/A, 8%, N). = “
Ue See ee
4,06) *
3.9.3. Finding A When Given F ye!
n on
Takin, i i a 7 hal ¢ ie
faking Equation 3-6 and solving for A, one finds that jue t) ( y 05)
a eae, (3-10)
a=Flaae=al wh |
‘A,of a uniform series
Thus, Equation 3-10 is the relation for finding the amount, A, of Sent
Of cash flows occurring at the end of N interest periods that woul
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3.9.4
couarren 3 /- Money=Tive RevaTionsirs AND EaUvALENCE
urring at the end of the
sinking fund factor, Numeric,
ann of the tables in Appendix C fo,
inctional symbol (A/F, i%,N)
alent value occ
qui
is called
to (have the same value as) its future €
xth colt
last period. The quantity in bracket
the
values for this factor are given the Ful
a wide range of values of and N. We shall use the
for this factor. Hence
Ae F(A/E,i%/N) (3-11)
ersonal savings totaling $1,000,009
ld. If the annual interest rate will
‘account, what equal end-of-year
EXAMPLE 3-3
‘An enterprising student is a
when she retires at age 65
the next 45 yee
average 7% over
BF must she save to accomP!
lanning to have Ps
fe is now 20 years
ars on her savings
ish her goal?
amount must
nual amount this student must
000,000. The equal anr
45 years at 7% annual interest
so.urion
1,
Be el $1,000,000 in
ture amou
oe fund that grows tO
place in a sinking
‘A = $1,000,000 (A/F, 7%, 45)
= $1,000,000(0.0035)
= $3,500
(sce Table C-10) is
together with a cash flow diagram
‘Another example of this type of problem,
and solution, is given in Table 3-3.
Finding A When Given P
Taking Equation 3-8 and solving for A, one finds that
= ia + aN
usa ala + ON (3-12)
Thus, Equation 3-12 is the relation for finding the amount, A, of a uniform series
of cash flows occurring at the end of each of N interest periods that would be
equivalent to, or could be traded for, the present equivalent P, occurring at the
beginning of the first period. The quantity in brackets is called the capital recovery
{factor.* Numerical values for this factor are given in the seventh column of the
tables in Appendix C for a wide range of values of i and N. We shall use the
functional symbol (A/P, i%, N) for this factor. Hence
A = P(A/P,i%,N) (09)
“The capital
recovery factor is more convenien ; .
hand-held calculator. more conveniently expressed as i/[1 ~ (1 + i)-] for computation witha
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39 / Relatin
An example that utilizes the equivalence between a present
cunt and a series of equal uniform annual payments starting a
ne and continuing through year four is provided in Taki 31 a
fon 3-13 yields the equivalent value of A that Tepays the $8,000
interest per year over four years
A = $8,000(4/P, 10%, 4) = $8,000(0:3155) = $2594
The entries in columns three and five of Plan 3 in Table 3-1 can now be better
understood. Interest owed at the end of year one equals $8,00n¢ 10), and there-
fore the principal repaid out of the total end-of-year Payment of §25594 je ge,
difference, $1,724. At the beginning of year two, the amount :
$8,000 ~ $1,724 = $6,276, Interest owed at the end
$628, and the principal repaid at that time is $2,524. ~ $628
entries in Plan 3 are obtained by performing, these calcul
and four.
lump-sum Joan
the end of year
S Plan 3, Equa-
loan plus 10%
$1,896. The remaining
lations for years three
that 10% interest is being paid on the beginning-of-year amount owed
year-end payments of $2,524, consisting of interest and principal
owed to $0 at the end of the fourth year. (The exact value of an $2,523.77 and
Produces an exact value of $0 at the end of four years, It is important t
Another example of a problem where we desire to compute an equiv
value for A, from a given value of P and a known interest rate and number of
compounding periods, is given in Table 3-3,
For an annual interest rate of 10%, the reader should now be convinced from
Table 3-3 that $1,000 at the beginning of year one is equivalent to $187.45 athe
end of years one through eight, which is then equivalent to $2,143.60 at the and
year eight.
co $6,903.60
~ [Repay
‘Amount $2524 481756
mount _
“o sam esax
“| Repay
$2,524
= Ea
a
2 Ey 4
End of Year
FIGURE 3-7 _ Relationship of Cash Flows for Plan 3 of Table 3-1 to Repayment of the
$8,000 Loan Principal
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yl aee eeede 1e Compounding Interest Factors and Symbols?
Factor by Which to Factor
To Find: Given: Multiply ‘Given’? Factor Name Functional
Symbol?
For single cash flows: :
: P a+ay Single payment
1 compound amount (F/P, i%, N)
7. F a7 Single payment
a+ present worth (P/E, i%,N)
For uniform series (arnnuities):
F 7 a+ i = Uniform series
i compound amount (F/A, i%, N)
p yn a+aN Uniform series
i(1 + present worth (PLA, i%, N)
i
A F ae Sinking fund (A/E,i%, N)
il + DN 7
A P apes Capital recovery (A/P, i%,N)
per interest period; N;, number of interest periods; A, uniform series amount (occurs at the end
F, future equivalent; P, present equivalent.
ghout this book.
+i, effective interest rate
of each interest period);
'The functional symbol system is used throu;
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90
cMaten 3 J) MONE
wt TTT
ime Pre
Period
Defesred Annuity (Uniform Series)
sdinary annuity has been
‘is. Remember that in
The end of periag
entire framed 0
“time 0," by J perio
payment iS
Lin length.
tat t fan annuity with cash flows of
at al
3.9, AP/A, M,N ~ P). The present equivalent ofthe
a yas of time 0 will then be
portray
aved fora
annuity d
assuming, that
nt oquivale
fom Equation
amount 4 is, 6 a
amount A(P/A, M,N
gle
; A(P/A, i%,N ~ (P/E i%,])
EXAMPLE 3-9 *
a father, on the day his son
strate the preceding discussion, suppose that 1
Tape wishes % amount would have to be paid into an
is born, wishes to determine what Lut
se orm pearing interest of 12% per year to provide withdrawals of $2,000 on each
of the son's 18th, 19th, 20th, and 2ist birthdays.
SOLUTION ;
The problem is represented in Figure 3:9. One should first recognize that an
ordinary annuity of four withdrawals of $2,000 each is involved, and that the
present equivalent of this annuity occurs at the 17th birthday when a (P/A,i%,
N — factor is utilized. In this problem, N = 21 and = 17. [tis often helpful to
use a subscript with P ot F to denote the respective point in time. Hence
Pir = A(P/A,12%,4) = $2,000(3.0373) = $6,074.60
Note the dashed arrow in Figure 3-9, denoting Pir. Now that Piz is known, the
next step isto calculate Po, With respect to Pp, Pr7 i a future equivalent, and hence
it could also be denoted Fir. Money at a given point in time, such as the end of
A= $2,000
FIGURE 3-9
Cash Flow Diagram of the Deferred
‘Annuity Problem in Example 3-9
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3.12
3.42 7 Equi
'quivalence Calculations Involving Multiple Interest Formulas 1
A= $2,000
er er ee ee
Ye ' :
ears | FIGURE 3-10
| Cash Flow Diagram for the
Deferred Annuity Problem
in Example 3-10
period 17, is the same regardless of whether itis called a present equivalent or a
future equivalent. Hence
Pp = Fir(P/F,12%, 17) = $6,074.60(0.1456) = $884.46
which is the amount that the father would have to deposit on the day his son iS
born.
EXAMPLE 3-10 ;
ose that the father wishes to
‘As an addition to the problem in Example 3-9, supp
Jeterine the equivalent worth ofthe four $2,000 withdrawals a5 of the son’s 24th
.drawn or possibly
birthday. This could mean that four amounts were nevet with
that the son took them and immediately redeposited them in an account also
earning interest at 12% per year. Using our subscript system, we wish to calculate
Fy, as shown in Figure 3-10 above.
SOLUTION
One way to work thisis to calculate
Fy = A(E/A,12%,4) = $2,000(4.7793)
Fa, can now be denoted Pay, and
Fog = Pal E/P,12%,3) = $9,558.60(1.4049) = $13,428.88,
fo work the problem is to recognize that Pi7
ih equivalent to the four $2,000 withdrawal
Using Po, we obtain
= $13,424.86
= $9,558.60
To determine F2s,
$6,074.60
. Hence one
‘Another, quicker way |
and Po = $884.46 are ea
gan find Fx, directly, given Pa ot Po
Foy = Po(F/P,12%, 24) = $884.46(15.1786)
the previous answer. The two numbers differ by $4.02,
ates
which closely approximé
to round-off error in the interest factors.
which can be attributed
alence Calculations Involving
ple Interest Formulas
jer should now be comfortable with equivalence problems that involve
if interest and discrete cash flows. All compounding of
Equi
Multi
The read
discrete compounding o'
@ scanned with OKEN Scanner—_=
2 cuarren 3 Mover—Tive ReLanoNshs aX0 EQUVALENCE.
interest takes place once per time period (e.g:, a year), and to this point cash flows
falso occur once per time period. This section provides two examples involving two
oor more equivalence calculations to solve for an unknown quantity. End-of-year
cash flow convention is used. Again, the interest rate is constant over the N time
periods.
KK
EXAMPLE 3-11
igure +11 depicts an example problem with a series of year-end cash flows |
extending over eight years. The amounts are $100 for the first year, $200 for |
the second year, $500 for the third year, and $400 for each year from the fourth
through the eighth. These could represent something like the expected maintenance
expenditures for a certain piece of equipment or payments into a fund. Note that
the payments are shown at the end of each year, whichis a standard assumption
(convention) for this book and for economic analyses in general unless one
has information to the contrary. It is desired to find the (a) present equivalent
expenditure, Pr; (b) future equivalent expenditure, Fs; and (c) annual equivalent
expenditure, A, of these cash flows ifthe annual interest rate is 20%,
SOLUTION
(a) To find the equivalent Pp, one needs to sum the equivalent values of all
payments sof the beginning of the first year (time zero). The required movements
of money through time are shown graphically in Figure 3-11a.
Py = Fi(P/F, 20%, 1) = $100(0.8333) =$ 83.33
+ Fy(P/F,20%, 2) + $200(0.6944) + 138.88
+ Fs(P/F, 20%, 3) + $500(0.5787) + 289.35
+A(P/A,20%,5) x (P/F, 20%,3) + $400(2.9900) x (0.5787) + 692.26
$1,203.82
(0) To find the equivalent Fs, one can sum the equivalent values of all payments as
of the end of the eighth year (time eight). Figure 3-11b indicates these movements
of money through time. However, since the equivalent Po is already known to be
$1,203,82, one can calculate directly
Fg = Po(F/P,20%,8) = $1,203.82(4.2998) = $5,176.19
(c) The equivalent A of the irregular cash flows can be calculated directly from
either Po or Fy as follows:
A = Po(A/P, 20%, 8) = $1,203.82(0.2606) = $313.73
or
A = Fe(A/F,20%,8) = $5,176.19(0.0606) = $313.73
The computation of A from Pp and Fs is shown in. Figure 3-11c. Thus, one finds that
the irregular series of payments shown in Figure 3-11 is equivalent to $1,203.82 at |
time zero, $5,176.19 at time eight, or a uniform series of $313.73 at the end of each |
of the eight years, !
@ scanned with OKEN Scanner3.12 J Equivalence Calculations Involving Multiple Interest Formulas 93
@
ry $100
be (PM, 20% 1) $200
_—
x16, 20%, 2)
——an
er
po Y Py= $1,208.82 z ee
7
ws =
$400 $400 $400 $400
400
$500 oo
x X(E/A, 20%, 5) 3
= 85,176.19
©
A
x(AP, Or) ee x (AFF, 20%, 8)
ee
i Fg (Grom b)
(from a)
FIGURE 3-11 Example 3-11 for Calculating the Equivalent P, F, and A Values
*
EXAMPLE 3-12
Transform the cash flows on the left-hand side of Figure 3-12 to their equivalent
cash flows on the right-hand side. That is, take the left-hand quantities as givens
and determine the unknown value of Q in terms of H in Figure 3-12. The interest
rate is 10% per year. (Notice that “<=>” means “equivalent to.”)
@ scanned with OKEN ScannerCHAPTER 3 J Money—Twwe ReLaTionsiiPs AND EQUIVALENCE
peel
eo ‘Trrtse ty
Endoof year(EOY) |
12345678
End of year (EOY)
1
Q
FIGURE 3-12 Cash Flow Diagrams for Example 3-12
soturion
If all cash flows on the left are discounted to year zero, we have P, =
2H{P/A,10%, 4) + H(P/A,10%.3\P/F,10%,5) = 7.8839H. When cash flows on
the right are also discounted to year zero, we can solve for Qin terms of H. [Notice
that Q at the end of year (FOY) two is positive, Q at EOY seven is negative, ang
the two Q values must be equal in amount]
7.8839H = Q(P/F, 10%,2) ~ Q(P/F, 10%, 7)
Q = 25.172H __ |
EXAMPLE 3-13
Suppose you start a savings plan in which you save $500 each year for 15 years,
You make your first payment at age 22 and then leave the accumulated sum in
the savings plan (and make NO more annual payments) until you reach age 65,
at which time you withdraw the total accumulated amount. The average annual
interest rate you'll earn on this savings plan is 10%,
A friend of yours (exactly your age) from Minnesota State University waits 10
years to start her savings plan (ie., she is age 32). She decides to save $2,000 each
year in an account earning interest at the rate of 10% per year. She will make these
annual payments until she is 65 years old, at which time she will withdraw the
total accumulated amount,
How old will you be when your friend’s accumulated savings amount (including
interest) exceeds yours? State any assumptions you think are necessary.
or
SOLUTION
Creating cash flow diagrams for Example 3-13 is an important first step in solving
for the unknown number of years, N, until the future equivalent values of both
savings plans are equal. The two diagrams are shown in Figure 3-13, The future
equivalent (F) of your plan is $500(F/A, 10%, 15)(F/P,10%,N ~ 36), and that
of your friend is F’ = $2,000(F/4, 10%,N — 31). It is clear that N, the age at
which F = F', is greater than 32. Assuming that the interest rate remains constant
@ scanned with OKEN Scannerlents 95
3.13 / Relating a Uniform Gradient of Cash Flows to Its Annual and Present Equival
Your savings plan: '
End of year (BOY)
id of year ( a
A= $500/year
Your friend's savings plan: i
End of year (OY) on
5 36 '
B38 5
A’ = $2,000/ year
FIGURE 9-13 Cash Flow Diagrams for Example 3-13
at 10% per year, the value of Ncan be determined by tral and error:
's F_Friend’s F
N__ Your Pla
36 $15,886 «$12,210
38 $19,222 $18,974
39 $21,145 $22,872
40 $23,259 $27,159
end’s accumulated savings will exceed yours.
£$500, you would be over 76 years old when
foral: Start saving early!)
By the time you reach age 39, your fi
(if you had deposited $1,000 instead o
your friend’s plan surpassed yours.
Interest Formulas Relating a Uniform
Gradient of Cash Flows to its Annual
and Present Equivalents
Some problems involve receipts or expenses that are projected to increase or
decrease by a uniform amount each period, thus constituting an arithmetic sequence
of cash flows. For example, because of leasing a certain type of equipment,
maintenance and repair savings relative to purchasing the equipment may increase
by a roughly constant amount each period. This situation can be modeled with a
uniform gradient.
Figure 3-14 is a cash flow diagram of a sequence of end-of-period cash flows
increasing by a constant amount, G, in each period. The G is known as the uniform
gradient amount. Note that the timing of cash flows on-which the derived formulas
@ scanned with OKEN Scanner96
CHAPTER
3-1 Mowey—Tiwe Revanionstirs ano EouvaLehce
i= Effective Interest
Rate per Period
FIGURE 3-14
Cash Flow Diagram for a
Uniform Gracient increasing
by G Dollars per Period
and tabled values are based is as follows:
Endof Period __Cash Flows
1 0
2 G
3 2G
N-1 (N-2)G
N (W=DG
we
(w-2)6
(-3)G
3G
I
{
o | ft f
fs eee |
3 4 N-2 0 N-1 N
End of Period
Notice that the first flow occurs at the end of period two.
‘The future equivalent, F, of the arithmetic sequence of cash flows shown in Fig-
F = G(F/A,i%,N — 1) + G(F/A,i%,N = 2) +++
+ G(F/A, i%, 2) + G(F/A, i%, 1)
3.13.1. Finding F When Given G
ure 3-14 is
or
Nat
F= [ote
N-2
+Otn a,
+OePt, Gey et
= Sia +N 14 (1+ NP 4
+(1+ 9? + (14H) +1) -
NG
i
@ scanned with OKEN Scanner3.43 / Relat
‘ating a Uniform Gradient of Cash Flows to Its Annual and Present Equivalents 97
Nel NG
= >a + at] >
=
& = Srya,i%,N)- Me. (220)
;
Instead of working with future equivalent values, itis usually more practical to
deal with annual and present equivalents in Figure 3-14.
3.13.2 Finding A When Given G
From Equation 3-20, itis easy to develop an expression for A as fol
A= F(A/E,i,N)
. [Sevaam - NSlare, iN)
lows:
= $-amriny
ol
Stee
i! N 4
otal >
‘The term in braces in Equation 3-21 is called the gradient to uniform series conversion
factor. Numerical values for this factor are given on the right side of Appendix C
for a range of iand N values. We shall use the funétional symbol (A/G, #%,N) for
this factor. Thus
A = G(A/G,i%,N) (3-22)
3.13.3 Finding P When Given G
We may now utilize Equation 3-21 to establish the equivalence between P and G:
P = A(P/A,i%,N)
e(i Ne de
=¢[} all i +i |
(1+) -1-Ni
Sear |
: of aaet _ oN I (22)
Se
i] a+) (1+ 9h
The term in braces in Equation 3-28 is called the gradient to present equivalent
conversion factor. It can also be expressed as (1/i)[(P/A, i%,N) — N(P/F, i%,N)]-
@ scanned with OKEN Scanner3.13.4
[xaeree 3-15
Asa further example of the use of arithm
CHAPTER 3 / Money—Tiwe ReLaTionshiPs AND EQUIVALENCE
Numerical values for this factor are given in column 8 of Appendix C for a wide
assortment of i and N’ values. We shall use the functional symbol (P/G, 1%, N) for
this factor. Hence
P = G(P/G.i%.N) G24
Computations Using G
Be sure to notice that the direct use of gradient conversion factors applies when
there is no cash flow at the end of period one, as in Example 3-14. There may be
an A amount at the end of period one, but it is tr ated separal tely, ee isuated in
Examples 3-13 and 3-16. A major advantage of using gradient conversion factors
(.e., computational time savings) is realized when N becomes large.
EXAMPLE 3-14
As an example of the straightforward use of the gradient conversion factors,
suppose that certain end-of-year cash flows are expected to be $1,000 for the second
year, $2,000 for the third year, and $3,000 for the fourth year, and that if interest is
15% per year, it is desired to find the (a) present equivalent value at the beginning
of the first year, and (b) uniform annual equivalent value at the end of each of the
four years.”
SOLUTION
Observe that this schedule of cash flows fits the model of the arithmetic gradient
formulas with G = $1,000 and N = 4 (see Figure 3-14). Note that there is no cash
flow at the end of the first period.
(a) The present equivalent can be calculated as
Py = G(P/G, 15%,4) = $1,000(3.79) = $3,790
(b) The annual equivalent can be calculated from Equation 3-22 as
A = G(A/G, 15%,4) = $1,000(1.3263) = $1,326.30
Of course, once Py is known, the value of A can be calculated as
A = Po(A/P. 15%, 4) = $3,790(0.3503) = $1,326.30
etic gradient formulas, suppose that one
has cash flows as follows:
EndofYear___ Cash Flows (S)
1 5,000
2 6,000
3 ~7, 000
4 8,000
y
@ scanned with OKEN Scanner3.43 / Relatin,
ga Uni a
Horm Gradient of Cash Flows to Ite Annual and Present Equivalents 99
and that one wis
Pate alent ati = 15% per year using
Sriten y ca alent ati ery
s to calculate their present equ
interest formulas
SOLUTION
Aue schedule of cash flows is depicted in the top di
fom two diagrams of Figure 3-15 show how the original schedule can be broken
into two separate sets of cash flows, a uniform series of $5,000 payments, plus
an arithmetic gradient payment of $1,000 that fits the general gradient model for
which factors are tabled. The summed present equivalents of these two separate
sets of payments equal the present equivalent of the original problem. Thus, using
the symbols shown in Figure 3-15, we have
Por
iagram of Figure 3-15. The
Poa + Pog
= ~A(P/A, 15%, 4) ~ G(P/G, 15%, 4)
—$5,000(2.8550) — $1,000(3.79) = ~$14,275 - 3,790 = ~$18,065
be calculated with the
: The annual equivalent of the original cash flows could
aid of Equation 3-22 as follows
Ar = A+Ac
$5,000 — $1,000(A/G, 15%, 4) = $6,326.30
Ar is equivalent to Por because ~$6,326.30(P/A, 15%, 4) = — $18,061, whi
same value obtained previously (subject to round-off error).
End of Year
1 2 3 4
— i= 15%
' $5,000
000 $6000
Pars? $7,000 $8,000
Equals End of Year
1 2 3 4
f — i= 19%
t | ’
er A= $5,000
Plus End of Yea
1 2 3 4
ee
: $1,000
Pon? a an
$3,000
FIGURE 3-15 Example 3-15 Involving an Increasing Arithmetic Gradient
@ scanned with OKEN Scanner100 CHAPTER 3 / MoNey=Tiwe RELATIONSHIPS AND EQUIVALENCE
and of Year
:
1 2 2
| '
| ‘ ua
' A=$8,000
} ne
\ {sign of Gis positive) $3,000
} Pos $2,000
1 $1000
Coie = 15%
1 7 4
End of Year
FIGURE 3-16 Example 9-16 Involving a Decreasing Arithmetic Gradient
EXAMPLE 3-16
ithmeti formulas, suppose that one
For another example of the use of arithmetic gradient form
has cash flows that are timed in exact reverse of the situation depicted in Example
3-15, The top diagram of Figure 3-16 shows the following sequence of cash flows:
Endof Year___Cash Flows (S)
1 8,000
2 7,000
3 6,000
4 -5,000
Calculate the present equivalent at i = 15% per year using arithmetic grat
interest factors.
SOLUTION
‘The bottom two diagrams of Figure 3-16 show how these cash flows can be bro!
into two separate sets of cash flows. It must be remembered that the arithmetic
gradient formulas and tables provided are for increasing gradients only. Hence
one must subtract an increasing gradient of payments that did not occur. Thus
@ scanned with OKEN Scanner3.14 / Relating a Geometric Sequence of Cash Flows to Its Present and Annual Equivalent
alents 101
Por = Poa ~ Pog
= —A(P/A,15%, 4) + G(P/G, 15%, 4)
= —$8,000(2.8550) + $1,000(3.79)
= —$22,840 + $3,790 = —$19,050
Again, the annual equivalent of the ori;
be calculated by the same rationale:
A=A-Ac
= —$8,000 + $1,000(A/G, 15%, 4)
= ~$6,673.70
Note from Examples 3-15 and 3-16 that the present equivalent of —$18,065 for
an increasing arithmetic gradient series of payments is different from the present
equivalent of — $19,050 for an arithmetic gradient of payments of identical amounts
but reversed timing. This difference would be even greater for higher interest rates
and gradient amounts and exemplifies the marked effect of timing of cash flows
on equivalent values. It is also helpful to observe that the sign of G corresponds to
the general slope of the cash flows over time. For instance, in Figure 3-15 the slope
of the cash flows is negative (G is negative), whereas in Figure 3-16 the slope is
positive (G is positive).
ginal decreasing series of cash flows can
® scanned with OKEN ScannerCastiriee = =
EXAMPLE 9-17
eometric sequence of cash flows in Figure 3-19 a
ider the end-of-year § \ » of increase is
Consi the P. A, Ao, and F equivalent values. The rate of increase is 29%,
a 4
eal the first year, and the interest rate is 25% per year.
year d ,
goLUTION
$833.33(P/A, 4.167%, 4)
$1,000 25% — 20% 4
(rvs 1.20 °
3 (1.04167)* = 1
= $8335. 0:04167(1.04167)*
= $833.33(3.6157) = $3,013.08
A = $3,013.08(A/P, 25%, 4) = $1,275.86
‘Ag = $3,013.08(A/P, 4.167%, 4)
4
0.04167(1.04167) = $833.34
= ssi] abaent = 1
F = $3,013.08(F/P, 25%, 4) = $7,356.15
EXAMPLE 3-18
Suppose that the geometric gradient in Example 3-17 begins with $1,000 at the end
of year one and decrenses by 20% per year after the first year. Determine P, A, Ag,
and F under this condition. ‘
SOLUTION
The value off is -20% in this case and icg = [(1+4)/(1+f)]-1 = (1.25/0.80)-1 =
0.5625, or 56.25% per year. The desired quantities are as follows: ey
$1,000
= “Fg (P/A,56.25%,4) = $1,250(1.4795)
= $1,849.38
P
@ scanned with OKEN Scanner345 1 Interest Rates That Vary with Time j0F
A = $1,849,38(A/P,25%, 4) = $783.03
Ag = $1,849,38(A /P,56,25%, 4) = $1,250.00
F = $1,849,38(F/P, 25%, 4) = $4,515.08
arr
3.15 Interest Rates That Vary with Time
eserve
When the interest rate on a loan can vary with, for example, the Federal R
Board’s discount rate, it is necessary to take this into account when determining
the future equivalent value of the loan. It is becoming common to see interest-rate
“escalation riders” on some types of loans. Example 3-19 demonstrates how this
situation is treated.
EXAMPLE 3.19
A person has made‘an arrangement to borrow $1,000 now and another $1,000 two
years hence. The entire obligation is to be repaid at the end of four years. If the
Projected interest rates in years one, two, three, and four are 10%, 12%, 12%, and
14%, respectively, how much will be repaid as a lump-sum amount at the end of
four years?
SOLUTION
This problem can be solved by compounding the amount owed at the beginning
of each year by the interest rate that applies to each individual year and repeating
this process over the four years to obiain the total future equivalent value:
F, = $1,000(F/P, 10%,1) = $1,100
F, = $1,100(F/P, 12% 1) = $1,232
Fs = ($1,232 + $1,000)(F/P, 12%, 1) = $2,500
Fy = $2,500(F/P, 14%,1) = $2,850
‘To obtain the present equivalent of a series of future cash flows subject to
varying interest rates, a procedure similar to the preceding one would be utilized
with a sequence of (P/F, ic%, ) factors. In general, the present equivalent value of
a cash flow occurring at the end of period N can be computed with Equation 3.32,
where i isthe interest rate forthe kth period (the symbol |] means “the product
of"):
p=— fy
TE iy (3-32)
For instance, if Fy = $1,000 and i, = 10%, iy = 12% j
= 13%, and is = 10%
1,000{(P/F, 10%, 1)(P/F, 12%, 1)(P/F, 139
13%, 1)(P/E, 10%,
7, 000|(0.9091)(0.8629)(0.8850)(0.9091)] = i St
p=
@ scanned with OKEN ScannerN EXAMPLE 3-20 |
A credit card company charges an interest rate of 1.375% per month on the unpaid
i hey claim, is 12(1.375%) = 16.5%,
balance of all accounts. The annual interest rate, t i
What is the effective rate of interest per year being charged by the company?
ict d on time periods that may be annual,
Interest tables in Appendix C are based on e ual,
quarterly, monthly, and so on. Because we have no 1.375% tables (or 16.5% tables),
Equation 3-33 must be used to compute the effective rate of interest in this example:
12,
i= ( + a -1
= 0.1781, or 17.81% /year |
Note that r = 12(1.375%) = 16.5%, which is the APR. It is true that r = M(r/M),
as seen in Example 3-20, where r/M is the interest rate per period.
t
|
1
® scanned with OKEN Scanner317.2
’ anyorest Preptea th compounding MOHe OA TaN One per,
1 Yoar
109
EXAMPLE 9:21
— ana SUD Tans HHO AVNET AOE 1D
sapposetnatasty for VO yearnaia vs
sores ped ter HW URE GT Swamnatinte
“ Wem OH We tent
‘ Oe as
SOLUTION
are four co"
pounding periods Pe YN, OLA AHL OEE 1 ty
riod is 0/4 = L5% When the vahten mercy’
ae seta
There
The interest rate Per interest pel
Equation 33, 07€ finds that
= SWOOSH) = Ststao
40) = $100.00(1L0)
p= PE/P.1S
e effective interest rate front
‘Alternatively, the ft
F ene P.6.14 10) = $100.00(1.0614)"" = a3 0: |
Torte
vas
quation INI is 1.1%, Therefor, |
nd Gradient Series
When there is more than one compounded interest period per year, the formula:
and tables for uniform series and gradient series can be used as Lg as there a
ar ow atthe end of each interest period, as shown in Figures 3-6 and 314 fora
cos inna series and a uniform gradient series respectively. °
Uniform Series a
EXAMPLE 3- 22
stone has a bank loan for $10,000, which is to be repaid in equal endo
Vi cont for five years with a nominal interest rate of 12% compounded
itis the amount of each payment? a
Suppose thi
monti instal
monthly. Whi
SOLUTION
The number of install
month is 12%/12 = 1%. When these
), and the interest rate per
one finds
fe
rp. A
‘A = P(A/P, 1%, 60) = $10,000(0.0222) = $222 \ ra
h month (interest period), including | Qn
ent payments is 5 X 12 = 60,
values are used in Equation 3
1268
that
Notice that there is a cash flow at the end of eacl
tmonth 60, in this example.
EXAMPLE 3.23
stain operating savings are expected to be Oat the end of the first six months,
at the end
bi Sonat he eu ofthe second ix months, at increase by $1,000
re pind heer fo total of four years, It is desired to find the
cauicakn nm amour, athe endl of each of the eight six-month periods if
jerest rate is 20% compounded semiannually.
@ scanned with OKEN Scanneruy ws saa som and regulations of siggy n2s/80” these methods ave often specified
States, and are used for d, fee te and municipal governments in the United
i rie Poses in other countries. In addition, as
We do not discuss the applicati
Internal Revenue Service
the Modified Accelerated
RS) non Of ACRS in the chapter, but eadily available
Cost Re lications describe its use.* Selected parts of
“covery System, however, are described and
'ystem applies to d
future engineering projects, ©preciable property in present and
fone Additional Definitions
any terms that are not generally included in the
lucation and practice, an abbreviated set of definitions
i iginal cost basis of the asset, adjusted by allowable
increases or decreases, is used to compute depreciation and depletion deduc-
tions! For example, the cost of any improvement to a capital asset with a useful
life greater than one year increases the original cost basis, and a casualty or
theft loss decreases it, If the basis is altered, the depreciation deduction may
need to be adjusted.
Basis, or cost basis The initial cost of acquiring an asset (purchase price plus
any sales taxes), including transportation expenses and other normal costs of
making the asset serviceable for its intended use. This amount is also called
the unadjusted cost basis.)
Book Value (BV) The worth of a depreciable property as shown on the accounting
records of a company. It is the original cost basis of the property, including
any adjustments, less all allowable depreciation ot depletion deductions. It
thus represents the amount of capital that remains invested in the property
and must be recovered in the future through the accounting process. The BV.
of a property may not be a useful measure of its market value.(In general, the
book value of a property at the end of year k is
k
_ABook value), = adjusted cost basis — >” (depreciation deduction), (6-1)
ja
Iseful references on material in this chapter, available from the Intemal Revenue Service in an
annually updated version, are Publication 534 (Depreciation), Publication 334 (Tay Guide for Small
Business), Publication 542 (Tix Information on Corporations), andl Publication 544 (Sales and Other
Dispositions of Assets).
@ scanned with OKEN Scanner248
S 634
capren 6) Devneonox avo Weowe TES
willing buyer £04 Willing
der no compuleya
Market value aay) Theamownt thal gage and is gh
fora prope ae Tee the present valle of vat lle Teeeige
buy or el The MY PT operty nell the time va mnt
through ownership
abasis of a property is ree
as arsover which the bast ;
Recovery period The number bees Tor the classical methods of eprecation Hs
through the accounting PrP MACRS, this period is the prop,
eriod is ee mm (GDS), ee is the class life for 4!
Glass for the General D syste (etn
“Alternative Dep! : System (1 form) for each year of the Macy,
Recovery APSTS pats utized te an annual depreciation dedy
i i to compute a a oe
recovery period ie ofa property at the end of is useful life,
ene it ic Then the asset can no longer be ys;
i ice of a property W ; “
Fa Te a atone
pro
i i nd these cash outflow:
ill ‘osing of the property, and t ot
ell incur expenses in disp tae to obtain a final net SV. When the classi
ted from the cash inflo' a ‘
veto of depreciation are applied, an estimated salvage value is initia
mMesblished and used in the depreciation ‘calculations. Under MACRS, the gy
"depreciable property is defined to be 2er0, i
pat tte The expected (est ‘od of time that a property will be use
mated) peri
ina trade or business or
come.jit is not how long the propery
ts to productively use it. Useful lie,
ual useful life of an asset, howeve,
to produce in
‘will ast but how long the owner expec
Sometimes referred to as depreciable life. Ac
may be different than its depreciable ife.
The Classical (Historical) Depreciation Methods
‘This section describes and illustrates the straight-line, declining balance, and sun.
of-the-years-digits methods of calculating depreciation deductions. As mentionsi
jin Section 6.2, these historical methods continue to apply, directly and indirect
to the depreciation of property. Also included is a discussion of the units o
production method.
Straight-Line (SL) Method
Straightline depreciation)is the simplest depreciation method. Itjassumes thts
constant amount is depreciated each year over the depreciable (useful) lft oth
asset The following definitions are used in the equations below. If we define”
N = depreciable life of the asset in years
cost basis, including allowable adjustments
dy = annual depreciation deduction in year k (1 = k = N)
“We often use the term Market Value (MY) in place of Salvage Value (SV).
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6.3 / The Classical (Historical) Depreciation Methods 247
BV; = book value at end of year k
SVw = estimated salvage value at end of year N
dj = cumulative depreciation through year k
then
d, = (B-SVy)/N (6-2)
dj = kd forl sk =N 63)
BV; = B-d; 4)
Note for this method you must have an estimate of the final SV, which will also
be the final book value at the end of year N. In some cases, the estimated SViw may
not equal an asset's actual terminal MV.
EXAMPLE 6-1
‘Anew electric saw for cutting small pieces of lumber in a furniture manufacturing
plant has a cost basis of 4,000 and a 10-year depreciable life. The estimated SV of
the saw is zero at the end of 10 years, Determine the annual depreciation amounts
using the straight-line method. Tabulate the annual depreciation amounts and the
book value of the saw at the end of each year. oe | BV
SOLUTION
The depreciation amount, cumulative depreciation, and book value for each year
are obtained by applying Equations 6-2, 6-3, and 6-4. Sample calculations for year
five are shown below.
= $2,000
BV; = $4,000 — a0 —9) = $2,000
‘
A a4
The depreciation and book value amounts for each year are shown below. s\° *
*
9
EOY,kK dr BV wee
: .)
argon - OSD
0
1 s4o0 (3,6
2 400 3,200
3 400 2,800"
4 400 2,400 -
5 400 2,000
6 400 1,600
7 400. 1,200
8 400 '800
9 400 400
0 400 0
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