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24-MMP-A4 Mine Valuation and Mineral Resource Estimation · December 2018

Question 27 of 29: Profitability Index of 6A and 6B

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

EGBC National Exam — Mining and Mineral Processing Engineering, 09-MMP-A4 Mine Valuation and Mineral Resource Estimation, 2018-Dec. 3 hours duration; one handwritten 8.5×11 in reference sheet permitted (not an open-book exam); only approved Sharp or Casio calculators allowed. Question 1 is compulsory (40 marks, parts 1.1–1.8); candidates then select THREE of the five optional Questions 2–6 (20 marks each) to complete the paper.

Reference texts: Isaaks & Srivastava, An Introduction to Applied Geostatistics (variogram modelling, kriging, anisotropy); Hustrulid, Kuchta & Martin, Open Pit Mine Planning and Design (mine valuation, NPV/IRR and cut-off grade methodology); Gentry & O'Neil, Mine Investment Analysis (smelter/refining contract terms, net smelter return, taxation and risk); Guilbert & Park, The Geology of Ore Deposits, and Evans, Ore Geology and Industrial Minerals (VMS/SEDEX and porphyry deposit models); SME Mining Engineering Handbook, 3rd ed. (mineral exploration/evaluation stages, ore reserve classification); CIM Best Practice Guidelines and NI 43-101 (Canadian Securities Administrators).

Question 6.6: Profitability Index of 6A and 6B (2 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Approach. $PI = 1 + NPV/Investment$, using the 15% NPVs from Question 6.5.

  1. 6A: $$PI_{6A}=1+\frac{11.00}{80}=\boxed{1.14}$$
  2. 6B: $$PI_{6B}=1+\frac{18.83}{80}=\boxed{1.24}$$
AlternativeProfitability Index @ 15%
6A1.14
6B1.24 (higher)

Since both alternatives require the identical USD 80M investment, PI ranks them identically to raw NPV here — 6B is preferred, generating USD 1.24 of present value per dollar invested versus 6A's USD 1.14. (PI would only diverge from an NPV-based ranking if the two alternatives required different amounts of capital.)