Engineering Economic Analysis

.

Applying Present Wort~ Techniques 161

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Two pieces of construction equipment are being analyzed:

Year

o 1 2 3 4 5 6 7 8

Alt.A

-$2000

+ 1000

+850

+700

+550

+400

+400

+400

+400

Alt.B

-$1500

+700

+300

+300

+300

+300

+400

+500

+600

Based on an 8% interest rate, which alternative should be selected?

.. "..SOUUTION'J'".'. -. I',,,-.. _ ~Joo;
AlternativeA
l00

r

~--850- - --- __ 700 -r- --- J

---1--==f===~--4r---i9---iF--~

0-1-2-3-4-5-6-7-8

1

2000

PW of benefits =400(PlA,8%, 8) +600(PI A,8%,4) - 150(PIG,8%,4)

= 400(5.747) + 600(3.312) - 150(4.650) -' 3588.50

PW of cost= 2000

Net present worth=3588.50- 2000 =+$1588.50

AlternativeB

I
I

I
r

L

.1

= = Ii::

,

I

1500

.~

I

I

I

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