Topic 8
Họ tên: 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 MR<MC
c) The monopolist will charge a price of 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-Q
2
A total revenue maximize when TR’=0
TR’=100-2Q=0
óQ=50 (units)
=> P= 100-Q=100-50= 50$
=> TR max= 100Q-Q2 = 100.50-50
2
= 2500$
Therefore, Q= 50 units
P= 50$
TR max= 2500$
c) Profit= TR-TC= 100Q-Q
2
- (500+4Q+Q
2
) = 96Q-2Q -500
2
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+Q
2
+8Q= 500+12Q+Q
2
Profit new= 100Q-Q
2
- (500+12Q+Q
2
)= 88Q-2Q -500
2
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+Q
2
+100=600+4Q+Q
2
Profit*= 100Q-Q
2
- (600+4Q+Q
2
)= 96Q-2Q -600
2
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-Q
2
MC= TC’=7$
Profit=TR-TC=15Q-Q
2
-7Q=8Q- Q
2
Profit maximize when Profit’=0
ó8-2Q=0
ó
Q
M
=4 (units)
=> P
M
=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) P
C
=MC=7$
P=15-Q
óQ
C
=8 (units)
DWL= ½ . (Q
C
- Q
M
) . (P
M
-P
C
) = ½ . 4. 4= 8$
Ex4:
a) TR=P.Q= (100-Q).Q=100Q- Q
2
AVC= VC/Q VC= Q
ó
2
+ 4Q
TC= VC+TC= Q
2
+ 4Q + 200
Profit= TR-TC= -2Q
2
+ 96Q -200
Profit maximize when Profit’=0
ó -4Q + 96=0
ó Q= 24 (units)
=> P=100-Q= 76$
=> Profit = 952$
b) P
max
= 100 (Q=0)
CS= ½ . Q . (P P)= ½ . 24. 24= 288
max
Socially Efficient Quantity (Q
PC
) : P=MC
ó 100-Q=2Q+4
ó Q= 32 (units)
MC= 2.24+4=52
DL= ½ . (Q
PC
Q). (P- MC) = ½ . 8. 24 = 96
c) Q
PPD
(Perfect Price Discrimination): Q
PPD
= Q = 32 (units)
PC
P
max
= 100 (Q=0)
MC
min
= 4 (Q=0)
PS
PPD
= ½ . (P
max
- MC
min
) . Q
PPD
= ½ . 96 . 32 =1536
d) PS= TR- VC = 100.24-24
2
- 24
2
- 4.24= 1152
PS’ = PS
PPD
- PS = 1536 1152 = 384

Preview text:

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