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Q 9,10 9. Consider a market in which the supply and demand curves are:. q 120-2

ID: 1108020 • Letter: Q

Question

Q 9,10

9. Consider a market in which the supply and demand curves are:. q 120-2 pb qs = 4 p where q and q are the quantities demanded and supplied, and pD and pS are the prices paid by the buyer and received by the seller, measured in dollars. a. Find the equilibrium in the absence of government intervention. Find consumer and producers surplus. b. Suppose that the government levies a tax of 6 dollars on each unit of the good exchange. Find the changes in consumer surplus, producer surplus, and the surplus collected by the government. Find the welfare costs of the tax. c. Suppose that the government instead places a subsidy of 3 dollars on each unit of the good exchanged. Find the new equilibrium. Find the changes in consumer surplus, producer surplus, and the surplus collected by the government. Find the welfare costs of the subsidy 10. Two firms are ordered by the federal government to reduce pollution. Firm A's marginal costs associated with pollution reduction is MC 20+40. Firm B's marginal costs associated with pollution reduction is MC-10+80. The marginal benefit of pollution reduction is MB-400-40 What is the socially optimal level of each firm's pollution reduction? Compare the social efficiency of three possible outcomes: a. b. i. require all firms to reduce pollution by the same amount. ii. charge a common tax per unit of pollution. iii. require all firms to reduce pollution by the same amount, but allow pollutionpermits to be bought and sold.

Explanation / Answer

a)qd=120-2pd and qs=4ps At equilibrium qd=qs suppose P is the price at that intersection 4P=120-2P this gives P=20 and hence qs=qd=80

Consumer surplus From Demand curve at qd=0 pd=60 hence area under the curve=1/2*(60-20)*80=1600

For Producer surplus from supply curve at qs=0 ps=0 hence area under the curve=1/2*(20-0)*80=800

b) if tax of $6 is levied the Pd=pd+6 in this case demand curve will become qd=120-2(pd+6) for equilibrium

qd=qs this will give P=18and qd=qs=72

consumer surplus will be at qd=0 pd=54 therfor consumer surplus=1/2*(54-18)*72=1296

similarily producer surplus=1/2*(18-0)*72=648

Surplus by government=6*72=432

Total surplus=1296+648+432=2376

Without intervention surplus(from a)=1600+800=2400

Welfare cost of Tax =2400-2376=24

c) In case of subsidy

qd=120-2(pd-3) Equilibrium Price=120-2(P-3)=4P this gives P=21 and Q=84

Consumer surplus=1/2*(63-21)*84=1764

Producer surplus=1/2*(21-0)*84=882

GOvernment surplus=-3*84=-252

Total surplus=1764+882-252=2394

Witghout intervention surplus=2400

Welfare cost =2400-2394=6