Answer:
Marginal cost: $13.70
Missing question:
Additional cost from increasing their output by one unit.
Step-by-step explanation:
The company will inccur only the variable cost as the fixed cost are within the relevant range:
Direct materials $ 6.85
Direct labor $ 3.60
Variable manufacturing overhead $ 1.25
Sales commissions $ 1.50
Variable administrative expense $ 0.50
Total variable cost: $13.70
producing an additional unit will genrate marginal cost for $13.70