Net Present Value of a Lease in Mining

Here you will find three different versions of a @RISK model used to value a gold mine lease.
1. A basic @RISK model with uncertainty in the amount of gold mined, the unit cost of extracting it, and the price of gold.
2. Same as the basic model, but provides the owner of the lease the option to abandon it at any time.
3. Same as the abandonment model, but where the Time Series Fit feature is used to fit historical gold prices to a time series process.