Final answer:
The new producer surplus after the price ceiling of $400 is imposed is represented only by area X, which is less than the original producer surplus of areas V + W + X at the equilibrium price of $600.
Step-by-step explanation:
To calculate the amount of producer surplus per month after a price ceiling is imposed, we need to focus on the given market scenario for a new drug. Before the price ceiling, the producer surplus was represented by the area V + W + X. Following the price ceiling of $400, firms reduce production to 15,000, and the new producer surplus is only area X.
Without the exact dimensions of these areas, an exact numeric answer cannot be provided. However, this scenario clearly demonstrates that the producer surplus has decreased due to the price ceiling, as producers are receiving less for the drug than they would at the equilibrium price. Consequently, the areas V and W are no longer part of the producer surplus after the price ceiling's imposition.