Oslo Company prepared the following contribution format income statement based on a sales volume of 1,000 units (the relevant range of production is 500 units to 1,500 units): Sales $ 40,000 Variable expenses 26,000 Contribution margin 14,000 Fixed expenses 8,680 Net operating income $ 5,320 4. If sales increase to 1,001 units, what would be the increase in net operating income?