Thursday, February 21, 2013

Supply & Demand | Exercise on rent control agency of New York City


The rent control agency of New York City has found that aggregate demand is QD = 160 - 8P. 
Quantity is measured in tens of thousands of apartments. 
Price, the average monthly rental rate, is measured in hundreds of dollars. 

The agency also noted that the increase in Q at lower P results from more three-person families coming into the city from Long Island and demanding apartments. 

The city’s board of realtors acknowledges that this is a good demand estimate and has shown that supply is QS = 70 + 7P.

a.       If both the agency and the board are right about demand and supply, what is the free-market price? What is the change in city population if the agency sets a maximum average monthly rent of $300 and all those who cannot find an apartment leave the city?

b.      Suppose the agency bows to the wishes of the board and sets a rental of $900 per month on all apartments to allow landlords a “fair” rate of return. If 50% of any long-run increases in apartment offerings come from new construction, how many apartments are constructed?























ANSWER
a.       If both the agency and the board are right about demand and supply, what is the free-market price? What is the change in city population if the agency sets a maximum average monthly rent of $300 and all those who cannot find an apartment leave the city?

Set supply equal to demand to find the free-market price for apartments:
160 - 8P = 70 + 7P, or P = 6,
which means the rental price is $600 since price is measured in hundreds of dollars. Substituting the equilibrium price into either the demand or supply equation to determine the equilibrium quantity:
QD = 160 - 8(6) = 112
and
QS = 70 + 7(6) = 112.
The quantity of apartments rented is 1,120,000 since Q is measured in tens of thousands of apartments. If the rent control agency sets the rental rate at $300, the quantity supplied would be 910,000 (QS = 70 + 7(3) = 91), a decrease of 210,000 apartments from the free-market equilibrium.
Assuming three people per family per apartment, this would imply a loss in city population of 630,000 people. Note: At the $300 rental rate, the demand for apartments is 1,360,000 units, and the resulting shortage is 450,000 units (1,360,000 - 910,000).
However, excess demand (the shortage) and lower quantity demanded are not the same concept. The shortage of 450,000 units is the difference between the number of apartments demanded at the new lower price (including the number demanded by new people who would have moved into the city), and the number supplied at the lower price. But these new people will not actually move into the city because the apartments are not available.
Therefore, the city population will fall by 630,000, which is due to the drop in the number of apartments available from 1,120,000 (the old equilibrium value) to 910,000.

b.      Suppose the agency bows to the wishes of the board and sets a rental of $900 per month on all apartments to allow landlords a “fair” rate of return. If 50% of any long-run increases in apartment offerings come from new construction, how many apartments are constructed?

At a rental rate of $900, the demand for apartments would be 160 - 8(9) = 88, or 880,000 units, which is 240,000 fewer apartments than the original free-market equilibrium number of 1,120,000. Therefore, no new apartments would be constructed.

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