Whirly Corporation's contribution format income statement for the most recent month is shown below: Total Per Unit Sales (10,000 units) $350,000 $35.00 Variable expenses 200,000 20.00 Contribution margin 150,000 $15.00 Fixed expenses 135,000 Net operating income $ 15,000 Required: (Consider each case independently): 1. What would be the revised net operating income per month if the sales volume increases by 100 units? 2. What would be the revised net operating income per month if the sales volume decreases by 100 units? 3. What would be the revised net operating income per month if the sales volume is 9,000 units?