高階ECON-DEMA-010
Suppose both demand and supply decrease simultaneously. What is the certain effect on equilibrium price and quantity?
A. Price falls, quantity falls
B. Price rises, quantity falls
C. Quantity falls, price is indeterminate✓ 答案
D. Price rises, quantity is indeterminate
解說
Both curves shift left, so quantity unambiguously decreases. Price depends on the relative size of the shifts: if demand falls more, price falls; if supply falls more, price rises; thus price is indeterminate.