Suppose that the government imposes a price ceiling at a price of $10. The number of units that would be exchanged in this market would be
1) 150, since that is the equilibrium quantity and the price ceiling is below the equilibrium price.
2) 220 , since that is the number of units demanded at the price ceiling
(and the quantity demanded is greater than the quantity supplied)
3) 90, since that is the number of units supplied at the price ceiling
(and the quantity supplied is less than the quantity demanded)
4) 155 , since that is the average of the quantity demanded and the quantity supplied at the price ceiling