Answer:
The total monthly fixed manufacturing cost is $328,000.
Explanation:
For 4000 units, The direct materials cost is $99.2 per unit, the direct labor cost is $45.5 per unit, the manufacturing overhead cost is $94.
For 5000 units, The direct materials cost is $99.2 per unit, the direct labor cost is $45.5 per unit, the manufacturing overhead cost is $77.6.
Total manufacturing overhead for 4,000 units
= 
= $376,000
Total manufacturing overhead for 5,000 units
= 
= $388,000
The variable cost per unit
= 
= $12 per unit
Fixed costs
= Total cost - Total variable costs
= 
= $328,000