Final answer:
At the global wheat price of P = 200, the country will import 400 units of wheat. The equilibrium quantity without trade is 400 units at an equilibrium price of P = 400.
Social welfare is affected with likely increased consumer surplus and decreased producer surplus.
Step-by-step explanation:
To find the volume of imports of wheat and the social welfare impact, we need to calculate the equilibrium quantity without trade and determine the change once trade is introduced at the global wheat price.
The equilibrium price occurs where the quantity demanded (Qᵢ) equals the quantity supplied (Qᵤ). According to the given equations, Qᵤ = P and Qᵢ = 800 - P.
Setting them equal to each other, we get P = 800 - P; simplifying gives us 2P = 800, from which we find P = 400. When P = 400, the equilibrium quantity Qᵤ = Qᵢ = 400 units of wheat.
However, given that the global price of wheat is P = 200, domestic supply (Qᵤ) will be 200 units and domestic demand (Qᵢ) will be 600 units at this price.
Thus, the country will import the difference, which is 600 - 200 = 400 units of wheat.
Social welfare is generally measured by consumer and producer surplus. Introducing trade at the global price likely increases consumer surplus due to lower prices but may decrease producer surplus since domestic producers receive less for their wheat.
Detailed analysis would require additional information on consumer and producer surplus calculations.