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Topic 8
Họ và tên: Tô Phạm Minh Anh Ex1: a) b) Q=6 (units)
Because a profit-maximizing monopolist chooses the quantity where MR=MC
or the closest point where MR>MC before MRc) The monopolist will charge a price of 5.5$
Because at Q=6, the corresponding price in the demand column is 5.5$ d) The profit will be 17$
Because Profit= MR-MC=33-16= 17$ Ex2:
a) No, it isn’t. Because P=100-Q (downward-sloping demand curve), a
perfectly competitive firm faces a horizontal demand curve (price-taker) b) TR= Q.P= (100-Q).Q= 100Q-Q2
A total revenue maximize when TR’=0 TR’=100-2Q=0 óQ=50 (units) => P= 100-Q=100-50= 50$
=> TR max= 100Q-Q2 = 100.50-502 = 2500$ Therefore, Q= 50 units P= 50$ TR max= 2500$
c) Profit= TR-TC= 100Q-Q2 - (500+4Q+Q2 ) = 96Q-2Q2 -500
A profit maximize when Profit’=0 Profit’= 96-4Q= 0 óQ=24 (units) => P= 100-24= 76$ => Profit max= 652$ Therefore, Q= 24 units P = 76$ Profit max = 652$
d) TC new= 500+4Q+Q2 +8Q= 500+12Q+Q2
Profit new= 100Q-Q2 - (500+12Q+Q2 )= 88Q-2Q2 -500
A profit new maximize when Profit’ new=0 ó 88-4Q=0 ó Q=22 (units) => P= 100-22= 78$ => Profit= 468$ Therefore, Q=22 units P= 78$ Profit = 468$
e) TC*= 500+4Q+Q2 +100=600+4Q+Q2
Profit*= 100Q-Q2 - (600+4Q+Q2 )= 96Q-2Q2 -600
Profit* maximize when Profit*’=0 ó 96-4Q=0 óQ=24 (units) => P=76$ => Profit*= 652$ Therefor, Q= 24 (units) P= 76$ Profit=652$ Ex3: a) TR=P.Q=(15-Q).Q=15Q-Q2 MC= TC’=7$ Profit=TR-TC=15Q-Q2 -7Q=8Q- Q2
Profit maximize when Profit’=0 ó8-2Q=0 óQM=4 (units) => PM =11$ => Profit maximize= 16$ Therefore, Q= 4 units P= 11$ Profit maximize = 16$
Lerner index L= (P-MC)/P= (11-7)/11=4/11 => indicating some market power b) PC =MC=7$ P=15-Q óQC =8 (units)
DWL= ½ . (QC - QM ) . (PM -PC ) = ½ . 4. 4= 8$ Ex4: a) TR=P.Q= (100-Q).Q=100Q- Q2 AVC= VC/Q óVC= Q2 + 4Q TC= VC+TC= Q2 + 4Q + 200 Profit= TR-TC= -2Q2 + 96Q -200
Profit maximize when Profit’=0 ó -4Q + 96=0 ó Q= 24 (units) => P=100-Q= 76$ => Profit = 952$ b) Pmax= 100 (Q=0)
CS= ½ . Q . (Pmax – P)= ½ . 24. 24= 288
Socially Efficient Quantity (QPC ) : P=MC ó 100-Q=2Q+4 ó Q= 32 (units) MC= 2.24+4=52
DL= ½ . (QPC – Q). (P- MC) = ½ . 8. 24 = 96
c) QPPD (Perfect Price Discrimination): QPPD = QPC = 32 (units) Pmax = 100 (Q=0) MCmin = 4 (Q=0)
PSPPD = ½ . (Pmax - MCmin ) . QPPD = ½ . 96 . 32 =1536
d) PS= TR- VC = 100.24-242 - 242 - 4.24= 1152
PS’ = PSPPD - PS = 1536 – 1152 = 384