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 Variable expenses $ 20,000 12,000 Contribution margin Fixed expenses 8.000 6,000 Net operating Income $ 2.000 13. Using the degree of operating leverage, what is the estimated percent increase in net operating income of a 5% increase in sales? % Increase in net operating income