"Assume zero rates and no other costs or benefits, gold spot is $$1900,$ and a broker is quoting you a $1-$year forward price on gold at $$2000.$ You can lock in an arbitrage profit by $[]("\text{'}$long$"\text{'}$ or $"\text{'}$short$"")$ the forward at $K=2000$ and $|("\text{'}$buy$"\text{'}"$ or $"\text{'}$sell$"\text{'})$ the gold on the spot market with bank financing $($either borrow from bank or save money to bank$)$ today. This will lock in a profit of dollars $($use integer$)$ at $1-$year expiry per each unit $("\text{'}$share$"\text{'})$ of gold you trade."