Within the relevant range, variable costs can be expected to: Multiple Choice vary in total in direct proportion to changes in the activity level. remain constant in total as the activity level changes. increase on a per unit basis as the activity level increases. increase on a per unit basis as the activity level decreases. Contribution margin is: Multiple Choice Sales less cost of goods sold. Sales less variable production, variable selling, and variable administrative expenses. Sales less variable production expense. Sales less all variable and fixed expenses. Given the cost formula Y = $23,000 + $8X, total cost at an activity level of 7,000 units would be: Multiple Choice $33,000 $79.000 $23.000 $56.000