How will each of the following changes in demand and/or supply affect equilibrium price and equilibrium quantity in a competitive market; that is, do price and quantity increase or decrease, or are the answers indeterminate because they depend on the magnitudes of the shifts?
a. supply decreases and demand is constant.
price:
quantity
b. demand decreases and supply is constant.
price:
quantity:
c. supply increases and demand is constant.
price:
quantity:
d. demand increases and supply increases.
price:
quantity:
e. demand increases and supply is constant.
price:
quantity:
f. supply increases and demand decreases.
price:
quantity:
g. demand increases and supply decreases.
price:
quantity:
h. demand decreases and supply decreases.
price:
quantity:

Explanation:

a. If supply decreases then the supply curve shifts to the left. If demand remains constant the equilibrium price increases and the equilibrium quantity decrease.  

b. If demand decreases then the demand curve shifts to the left. If supply remains constant the equilibrium price decreases and the equilibrium quantity decrease.

c. If supply increases then the supply curve shifts to the right If the demand remains constant the equilibrium price decreases and the equilibrium quantity increases.

d. If demand increases then the demand curve shifts to the right. If supply increases, then the supply curve shifts to the right. The equilibrium price is undetermined because it depends on the shift’s magnitude but in all cases the equilibrium quantity increases.

e. If demand increases then the demand curve shifts to the right. If supply remains constant the equilibrium price increases and the equilibrium quantity increase.

f. If supply increases then the supply curve shifts to the right. If demand decreases, then the demand curve shifts to the left. The equilibrium price is undetermined, and the equilibrium quantity always decreases.

g. If demand increases then the demand curve shifts to the right. If supply decreases, then the supply curve shifts to the left. The equilibrium price is undetermined because it depends on the shift’s magnitude but in all cases the equilibrium quantity increases.

h. If demand decreases (shift to the left) and supply decreases (shift to the left). The equilibrium price in all cases decreases and the equilibrium quantity is undetermined because it depends on the shift’s magnitude