Suppose the demand and supply functions for milk are given by the equations:
QD=200/P
30=-QS+5P
Solution:
1.). At equilibrium: QDÂ = QS
QDÂ =Â "\\frac{200}{P}"
QSÂ = -30 + 5P
"\\frac{200}{P} = -30 + 5P"
Multiply both sides by P:
200 = -30P + 5P2
Solve for P using the quadratic formula:
P = 10
Equilibrium price = 10
Substitute in the QDÂ function to derive quantity:
QDÂ =Â "\\frac{200}{P}"
QDÂ =Â "\\frac{200}{10} =20"
Equilibrium quantity = 20
2.). QDÂ =Â "\\frac{200}{P}"
QSÂ = -30 + 5P
The tax of $12 added will only affect the supply curve:
New supply curve after tax:
QSÂ = -30 + 5P
QS = -30 + 5(P – 12)
QS = -30 + 5P – 60
QSÂ = -90 + 5P
New equilibrium after tax:
QDÂ = QS
"\\frac{200}{P}"Â = -90 + 5P
Multiply both sides by P:
200 = -90P + 5P2
Solve for P using the quadratic formula:
P = 20
New equilibrium price = 20
Substitute in the QDÂ function to derive quantity:
QDÂ =Â "\\frac{200}{P}"
QDÂ =Â "\\frac{200}{20}"Â = 10
New equilibrium quantity = 10
3.). A relevant sketch of 1 and 2 is as below:
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4.). The tax borne by the producer and consumer:
Tax borne by the producer = (10 – 8) "\\times" 10 = 2 "\\times" 10 = 20
Tax borne by the consumer = (20 – 10)"\\times" 10 = 10 "\\times" 10 = 100
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5.). Tax yield = Tax borne by the producer + tax borne by the consumer
Tax yield = 20 + 100 = 120
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6.). The fraction of the tax borne by the consumer is =Â "\\frac{100}{120} = \\frac{5}{6}\\; or \\; 83.3\\%"
The fraction of the tax borne by the producer is =Â "\\frac{20}{120} = \\frac{1}{6}\\; or \\; 16.7\\%"
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7.). The arc price elasticity of demand formula =Â "=\\frac{\\%\\;change\\; in\\; quantity\\; demanded}{\\%\\; change\\; in\\; price}"
="=\\frac{Q_{2} -Q_{1}}{(Q_{2}+Q_{1})\/2 } \\div \\frac{P_{2} -P_{1}}{(P_{2}+P_{1})\/2 }"
Q1Â = 20
P1Â = 10
Q2Â = 10
P2Â = 20
"\\frac{10 -20}{(10+20)\/2 } \\div \\frac{20 -10}{(20+10)\/2 } = \\frac{-0.67}{0.67} = 1"
The arc price elasticity of demand = 1, which means that it is unit elastic. This is a situation where a change in price results in an equally proportionate change in quantity demanded.
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The recommended price policy is to charge high prices and reduce costs. This is because any change in price will result in an equally proportionate change in quantity demanded. Increasing prices will result in an increase in total revenues.  Â
Comments
Thank you a million times! That was so helpful.
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