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Present Worth Index

Present worth index compares the present worth of savings or benefits to the required investment.

$$PWI=\frac{\text{Present worth of annual savings}}{\text{Investment}}$$

Problem 40: CE Board May 2017

Investment is P30,000, annual net savings is P12,600, useful life is 9 years, and MARR is 12%. Compute the present worth index.

$$P=12600(P/A,12\%,9)=12600(5.3283)=67,136.58$$
$$PWI=\frac{67,136.58}{30,000}=2.24$$

Final answer: 2.24.

Problem 41: Project Present Worth Index

A project has first cost $500,000 split between years 0 and 1. Net annual income of $90,000 begins at year 2 for 10 years. At 10%, calculate PWI.

Present worth at year 1 of the 10-year net annual income is $553,011, then discounted to year 0 gives $502,737.

$$PWI=\frac{502,737-250,000}{250,000}=1.01$$

Final answer: 1.01.

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