Project ForgePlant Design & Economics
Cost Estimation
GATE 2015
Hard
CT=100f1+1000/(f1f2)+20f2²+50. The lowest total cost CT (lakh Rs), rounded to 1 decimal place, is
572.8 lakh Rs(± 6 accepted)
Explanation
∂CT/∂f1=0 gives f1²f2=10; ∂CT/∂f2=0 gives f1f2³=25. Dividing: f2²/f1=2.5 ⟹ f1=0.4f2². Substituting: 0.16f2⁵=10 ⟹ f2≈2.287, f1≈2.091. CT≈209.1+209.1+104.6+50=572.8.
Source: GATE CH 2015 (2015)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.