Biz-Zaza Company prepared the following contribution income statement based on a sales volume of 1,000 units (the relevant range of production is 500 units to 1, 500 units): Sales: $20,000 Variable Expenses: 12,000 Contribution Margin: 8,000 Fixed Expenses. 6,000 Net Operating Income: 2,000 Answer each of the following questions independently and refer to the original data unless stated otherwise. What is the contribution margin per unit? What is the contribution margin ratio? What is the variable expense ratio