Evaluation of Underground Zinc Mine Investment Based on Fuzzy-Interval Grey System Theory and Geometric Brownian Motion

Table 4

Mine revenues over production period 2017–2021.

	2017	2018	2019	2020	2021
𝑅year (mill’s USD)	[2.279, 7.466]	[1.974, 7.360]	[1.672, 7.269]	[1.374, 7.192]	[1.079, 7.131]