Skip to main content

Best combination with independent and contingent projects

Short answer

Find PW of each project (A: 26,687, B: 18,026, C: 56,699). Feasible combinations within Rs. 120,000 budget and contingency B only with C. A+C yields highest PW of Rs. 83,385 at investment Rs. 90,000.

Select the best combination of the projects where A is independent and B is contingent on C.

ProjectABC
Initial Investment40,00070,00050,000
Annual Revenues15,00020,00020000
Annual cost2,5003,5000
Useful life (Yrs.)888
The investment is limited to Rs. 120,000. MARR = 10%.

A is independent; B is contingent on C (B can be taken only if C is taken). Budget = Rs. 120,000, MARR = 10%, life 8 years. Net annual benefit = revenue - annual cost.

(P/A, 10%, 8) = 5.3349

PW of each project

ProjectInvestmentNet benefit/yrPW = -I + NB(P/A,10%,8)
A40,00012,500-40,000 + 12,500(5.3349) = 26,687
B70,00016,500-70,000 + 16,500(5.3349) = 18,026
C50,00020,000-50,000 + 20,000(5.3349) = 56,699

Feasible combinations

Because B needs C, the combinations "B alone", "A + B" are infeasible. Remaining combinations (1 = taken):

CombinationABC
Do nothing000
A100
C001
A + C101
B + C011
A + B + C111

Budget test and PW

CombinationInvestment (Rs.)PW (Rs.)
Do nothing00
A40,00026,687
C50,00056,699
A + C90,00083,385
B + C120,00074,725
A + B + C160,000exceeds budget

Answer: Select A + C (investment Rs. 90,000), which has the highest PW of Rs. 83,385. The combination B + C uses the whole budget but gives only Rs. 74,725; A + B + C costs Rs. 160,000 and violates the limit. Each of A, B, C is individually profitable, so the budget and the contingency decide the result.

✓ Answer checked by Claude Opus 5.5 (high effort)

All Engineering Economics chapter 4 questions →