Exercise 6-1 The Effect of Changes in Activity on Net Operating ncome [LO6-1] Whirly Corporation's contribution format income statement for the most recent month is shown below: Required: (Consider each case independently): 1. What would be the revised net operating income per month if the sales volume increases by 90 units? 2. What would be the revised net operating income per month if the sales volume decreases by 90 units? 3. What would be the revised net operating income per month if the sales volume is 7,900 units