Answer:
$12.80
Explanation:
As we know, it the fixed cost component which remains same at all levels of activity, when the activity is in a relevant range.
When the activity changes there is an increment in cost, which is related to each unit produced: this is called variable component.
Any cost which is constant per unit, and changes in total with change in output is variable cost.
Here, variable cost are:
Direct material = $7.05
Direct Labor = $4.20
Variable manufacturing overhead = $1.55
Sales Commission = $1.15
Variable administrative expense = $0.40
Out of all the above cost components, the variable cost related to manufacturing each extra unit = Direct material + direct labor + variable manufacturing overhead = $7.05 + $4.20 + $1.55 = $12.80
Sales commission is chargeable only when goods are sold, and not when they are produced.
Administrative cost is not a manufacturing cost.
Therefore, incremental manufacturing cost = $12.80