Memorize these. Derivation is optional. Application is mandatory. Problem: You need backup power for a remote telecom tower. Two options:
over 10 years (two cycles) = [-8,000(A/P,8%,5) - 5,500 + 500(A/F,8%,5)] (same for both cycles, so just use one cycle — yes, because AW for one cycle = AW over LCM). = -8,000(0.25046) - 5,500 + 500(0.17046) = -2,003.68 - 5,500 + 85.23 = -$7,418.45 / yr
= -25,000 - 500(P/A,8%,10) + 2,000(P/F,8%,10) = -25,000 - 500(6.7101) + 2,000(0.4632) = -25,000 - 3,355 + 926 = -$27,429 engineering economy excelerated ebook
is not finance. It’s not accounting. It’s the bridge between technical feasibility and financial viability.
Second gen at year 5: (-8,000 + 500 salvage of first?) Wait — careful. Actually: Memorize these
Better: PW = -8,000 - 5,500(P/A,8%,5) + 500(P/F,8%,5) - 8,000 - 500 - 5,500(P/A,8%,5)(P/F,8%,5) But accelerated trick: Use instead.
| | Solar + Battery | Diesel Gen | |--------------|----------------|-------------| | Initial Cost | $25,000 | $8,000 | | Annual O&M | $500 | $2,500 | | Fuel cost | $0 | $3,000 (escalating 5%/yr) | | Lifespan | 10 years | 5 years (then replace) | | Salvage value | $2,000 | $500 | | MARR (hurdle rate) | 8% | 8% | Problem: You need backup power for a remote telecom tower
Master Time, Money, and Decision-Making in Half the Time Chapter 1: The Accelerated Mindset – Why Engineering + Economics Wins You’re an engineer. You solve problems. But in the real world, the best technical solution isn’t always the right one — unless it’s also profitable.