Answer:
20
Step-by-step explanation:
The marginal cost refers to the cost a company has when an additional unit is manufactured and it is calculated using the formula:
Marginal Cost= change in costs / change in quantity
Change in cost in this case is 20 as the last unit of labor hired costs an additional 20 per hour.
Change is quantity is 1 as the hourly production increases from 250 to 251 units.
Marginal Cost=20/1
Marginal Cost= 20
The marginal cost of the 251st unit of output was 20.