Bai Tap KTMT

Bi tp 1. Di y l mt phn ng cu ca ba c nhn v cht lng khng kh ca 3 vng ln cn. Cht lng khng kh (ch mang gi tr nguyn) c o bng g/m (micrograms kh SO2 c trong mt mt khi kh). Nu chi ph cn bin gim kh SO2 3 vng xung quanh l 40 $ cho mi g/m , mc cht lng khng kh hiu qu x hi l g, gi s rng x hi trong trng hp ny ch bao gm ba ngi ny. Chi ph x l kh SO2 ( la/microgram/m3) 60 50 40 30 20 10 0 Gii p: y l cu hi sinh vin thc hnh tm ng cu tng ca hng cng cng. Trc honh o mc cht lng khng kh tng ln theo chiu sang phi, c ngha gim kh SO2 trong khng kh. Trong trng hp ny ng tng cu c xc nh tng theo chiu dc sn lng chi tr ca c nhn: g/m3 1200 1100 1000 900 800 700 600 Tng gi sn lng chi tr cn bin (MWTP) 130 100 70 40 20 10 03

A 1.400 1.300 1.200 1.100 1.000 900 800

Lng cu B 1.200 1.100 1.000 900 800 700 600

C 1.500 1.400 1.300 1.200 1.100 1.000 900

ng tng cu khng c xc nh r rng ti mc cao hn 1200 g/m 3 c nhn B ch c bit n mc . Hiu qu t c mc 900 g/m .

ng cu

Bi tp 2: i vi bi tp 1, hy chng ming rng mc cht lng khng kh hiu qu x hi s ti a ho li ch rng x hi. Gii p: Sinh vin c th chng minh theo hai cch rng mc cht lng khng kh hiu qu x hi s ti a ho li ch rng x hi. S dng phng php 1, i vi mc cht lng khng kh trn 900, MWTP (li ch cn bin x hi) gim kh SO2 vt qu chi ph x l cn bin x hi. V vy, nu cht lng khng kh c ci thin, mc gim thit hi phi vt qu chi ph c c li ch rng x hi tng thm. Ngc li, nu chtEnvironmental Economics Teachers Manual 2005

7 lng khng kh di mc 900, gi sn lng chi tr cn bin nh hn chi ph x l cn bin(MAC). Bng cch gim cht lng khng khi mt n v, chi ph x l tit kim c s ln hn thit hi gim xung li ch rng tng thm. Thng d x hi khng th tng thm y nu MAC = MD (thit hi cn bin). Phng php th hai v th ng MWTP v MAC v s dng din tch pha di nhng ng ny tnh ton li ch rng x hi. Gi s ch s cht lng khng kh ban u l 1200, gi tr rng tng thm do lm sch n mc cht lng mi trng di y c minh ho sau y. Ch s cht lng khng kh 7500 1000 900 800 700 600 500 400 300 Tng WTP 11500 20000 25500 27500 29000 29500 29500 29500 29500 Tng chi ph 4000 8000 12000 16000 20000 24000 28000 32000 36000 Gi tr rng x hi 7500 12000 13500 (MAX) 11500 9000 5500 1500 -2500 -6500d

Cu 1. Nhu cu ca Alvin i vi nc ng chai c biu din qua th Q A = 8 0.5P. Hm cu ca Betty l QdB = 6 P. Hy tnh tng gi sn lng tr v gi sn lng tr cn bin ca Alvin v Betty cho 4 chai nc v minh ha bng th. p n: ng cu c nhn th hin lng nc ti a m mi c nhn sn lng mua ti mt mc gi. Sp xp li phng trnh theo mc gi, ta c mt hm biu din mc gi ti a m mi c nhn sn lng tr (gi sn lng tr bin; MWTP) cho n v th Q. MWTPA d d =16-2 Q A v MWTPB =6 - Q B. Vi lng cu l 4 n v cho mi ngi, MWTP ca Alvin l $8, trong khi MWTP ca Betty l $2. Tng WTP ca Alvin l din tch nm di d d ng WTP bin ca anh ta t Q A = 0 n Q A =4, v tng t cho Betty. Tng WTPA = (8 x 4) x [(16-8) x 4]/2 = $48. Tng WTPB = (2 x 4) x [(6-2) x 4]/2 = $16.

Environmental Economics Teachers Manual 2005

13

MWTP ($/n v)

16

MWTP

($/n v)

8 6 0 4 8 Qa 2 0 4 6 Qa

Cu 2. Vi cc phng trnh nh trong Cu 1, hy tnh tng cu i vi nc ng chai, gi nh rng Alvin v Betty nhng ngi tiu dng duy nht. Xc nh ng tng cu nu c 5 ngi c ng cu nh Alvin v 5 ngi c ng cu nh Betty. p n: tnh tng cu ca Alvin v Betty, cng gp lng cu ti mi mc gi (cng theo chiu ngang). ng cu s gp khc mc gi $6, ti Alvin mua 5 v Betty mua 0 n v sn phm. H s ct trn trc gi l $16 v trn trc lng l 14 n v. Vi mc gi t 0 n 6, c hai ngi tiu dng s c nhu cu v nc ng chai, tnh tng lng d cu s cho ta hm tng cu Q B & A = 14 3P/2. Vi mc gi cao hn $6, ch c Alvin l d c nhu cu, t c hm cu Q B & A = 16 2P. Vi 5 ngi tiu dng cho mi hm cu c nhn trn, hm tng cu cho 5 ngi ging d d Alvin v 5 ngi ging Betty tng ng l Q aggA = 40 2.5P v Q aggB =30 5P. ng tng cu ca 10 ngi l gp khc ti mc gi $6 v sn lng 25 n v. mc gi t 0 n 6, c th tm ra ng cu bng cch tnh tng lng cu ca 10 ngi d Q agg = 70 7.5P. Vi mc gi cao hn $6, ch c Alvin c nhu cu mua nc, vi tng d cu l Q agg = 40 2.5P. H s ct trn trc gi l $16 v trn trc lng l 55. MWTP 16 ($/n v)

10

0 5 14

Q

d

B&A


14

Cu 3. Nu gi ca bng tennis l $4 cho mi container, nhng nh sn xut sau y c th tip tc sn xut hay khng? Ti sao? Mi ngi s sn xut bao nhiu ti mc gi ny? p n: Mi doanh nghip s thu c thng d t nhn dng nu li ch bin m n nhn c ( y l $4 trn mt n v) cao hn chi ph bin sn xut ra n v sn phm . Doanh nghip s c li nu MC P, v n s l. Chng ta c th tm ra sn lng ca mi doanh nghip bng cch t MC = P = 4 v tm n s. i vi doanh nghip A, s s kt qu l 3 + 0.3 Q =4, t Q =3.33 (1,000 n v). Tng t, doanh nghip B khng th cung ng n v sn lng no, trong khi doanh nghip C s cung cp 30 (1,000 n v). Cu 4. ng cu ca mt c nhn i vi nc ung ng chai c biu din bi phng trnh: Q= 6- 0.5p + 0.0001I Vi Q l lng cu ti mc gi p khi thu nhn ca c nhn l I. Gi s ban u thu nhp ca c nhn ny l $40,000. a) Ti mc gi no th lng cu bng khng? Mc gi ny c gi l mc gi ti a (choke price) bi v n l mc gi trit tiu nhu cu. b) Nu gi tt ca nc ng chai l $10, lng cu l bao nhiu? c) Ti mc gi $10, co gin ca cu theo gi l bao nhiu? d) Ti mc gi $10, thng d tiu dng l bao nhiu? e) Nu gi tng ln $12, thng d tiu dng s gim bao nhiu? f) Nu thu nhp l $60,000, thng d tiu dng b mt l bao nhiu nu mc gi tng t $10 ln $12? p n: a) Q = 6 0.5p + 0.0001I Q = 6 0.5 p + 0.0001 (40,000) Q = 10 0.5p Ti Q =0 P =20 b) Q = 10 0.5 (10) = 5 c) co gin ca cu theo gi l (q/p) (p/q). Vi ng cu tuyn tnh nh phng trnh trong bi ny, (q/p) bng dc ca ng cu, v trong bi tp ny l 0.5. Do co gin ca cu theo gi l (-0.5) (10/5) = -1. Lu rng viEnvironmental Economics Teachers Manual 2005

15 ng cu tuyn tnh, co gin ca cu theo gi l khng c nh, gi tr tuyt i ca n tng khi mc gi tng. d) Thng d tiu dng l tam gic nm di ng cu (ngc) v trn mc gi cn bng. ng cao ca tam gic l mc gi ti a choke price tr gi tt (20-10 = 10) v y l lng cu (5). Din tch tam gic l (10) (5)/2=$25. e) Mc gi tng ln $12 lm lng cu gim xung 4 chai. Thng d tiu dng mi l (20-12) (4)/2=$16. Phn gim trong thng d tiu dng l $25-$16=$9. f) Khi thu nhp l $60,000, nh cu i vi nc ng chai l Q=6-0.5p+ (0.0001) (60,000) = 12 0.5p. Vi p = 10, q=7, v p=12, q=6, s thay i trong thng d tiu dng l (12-10) (6) + (2) (1)/2 = 13. S thay i trong thng d tiu dng tng ln theo thu nhp cho thy s ph thuc ca gi sn lng tr vo thu nhp. Cu 5. Gi s mt nh my xay bt g c t b sng Mekong. Chi ph t nhn bin (MC) ca vic sn xut bt g ($/tn) c biu din qua phng trnh: MC = 10 + 0.5 Y Vi Y l tn bt g c sn xut. Bn cnh chi ph t nhn bin cn c mt chi ph ngoi tc. Mi tn bt g s to ra mt lung nhim cho con sng, to ra mt thit hi $10. y l mt chi ph ngoi tc do cng ng gnh chu ch khng phi do ngi gy nhim. Li ch bin (MB) i vi x hi ca mi tn bt, tnh theo $, l: MB = 30 0.5 Y a) Hy v th minh ha chi ph bin (MC), li ch bin (MB), chi ph ngoi tc bin (EMC), v hm chi ph x hi bin.SMC = 20 +0.5Y MC =10 +0.5 Y

MB= 30-0.5Y EMC =10

Y*=10 b) Tm mc sn lng bt g ti a ha li nhun, gi s rng ngi bn c th t c doanh thu bin bng li ch bin ca x hi t bt g.Environmental Economics Teachers Manual 2005

16 MC = 10 + 0.5 Y MR = 30 0.5 Y MC = MR ti a ha li nhun: 10 + 0.5Y = 30 - 0.5Yta c Y* = 20.

c) Tm mc sn lng bt g ti a ha li ch x hi rng Vi MEC =10 SMC = MC + MEC = 10 + 0.5Y + 10 = 20 + 0.5 Y v ti a ha li ch x hi rng i hi: SMC = MB Suy ra: 20 + 0.5 Y = 30 0.5 Y = > Y* = 10. d) Chi ph ngoi tc bin phi l bao nhiu vic sn xut bt g khng cn ng mong mun i vi x hi? MC + MEC = MB 10 + 0.5Y + MEC = 30 0.5YDo , vi Y =0, MEC=20. Cu 6. Gi s mt c nhn c hm tha dng: U=E0.25

Y = 20 MEC.

+Y

0.75

Vi E l ch s cht lng mi trng v Y l thu nhp. T tnh hung ban u vi E =1 v Y=100, tnh CS v ES tm ra s thay i do E ln 2 v E gim xung 0.5. p n: Vi s ci thin cht lng mi trng E, ta c: U0 = 10.25

+ 100

0.75

= 32.6228 = 32.8120

U1 = 2

0.25

+ 100

0.75

CS l WTP cho s ci thin, do chng ta phi gii phng trnh: 32.6228 = 20.25

+Y

0.75

N

tm ra YN, nh sau:Environmental Economics Teachers Manual 2005

17

32.6228 = 1.1892 + Y Y0.75 N

0.75

N

= 31.4336

0.75ln(YN) = ln (31.4336) = 3.4479 ln (YN) = 4.5972 YN = 99.2032 Khi , CS = Y0- YN = 100 99.2032 = 0.7968 ES l WTA cho s ci thin b mt i, do ta phi gii: 32.8120 = 10.25

+Y

0.75

N

tm ra YN, kt qu l YN = 100.7928 Do ES = YN Y0 = 0.7928. Vi s gim st cht lng mi trng E, ta c: U0 = 10.25

+ 100

0.75

= 32.6228 = 32.4637

U1 = 0.5

0.25

+ 100

0.75

CS l WTA cho s thay i. Ta gii phng trnh: 32.6228 = 0.50.25

+Y

0.75

N

tm ra YN = 100.6815 kt qu l CS = YN Y0 = 100.6715 100 = 0.6715 ES l WTP khng xy ra s thay i, ta gii: 32.4637 = 10.25

+Y

0.75

N

tm ra YN = 99.3298, kt qu l ES = Y0 YN = 100 99.3298 = 0.6702 Cu 7. Ch c nhng tiu chun mi trng cao nht mi c th ti a ha phc li x hi. Hy bnh lun. p n: Pht biu ny ni ln rng cn phi huy ng mt cch khng gii hn cc ngun lc x l (hay phng chng) nhim hay suy thoi mi trng, bt k quy m ca li chEnvironmental Economics Teachers Manual 2005

18 m vic lm ny em li. Hiu qu kinh t i hi s cn bng gia li ch v chi ph bin. Tuy nhin, pht biu ny l ph hp vi vn hiu qu kinh t nu chi ph lm sch/ngn nga nhim lun bng khng, hay cc thit hi l ln v cng, hay ni mt cch tng qut hn, nu li ch bin di hn lun ln hn chi ph x l bin di hn cho n khi nhim c x l hon ton.

BI 5: KINH T NHIM MI TRNG CH 1: Mc nhim ti uNgun: Field, Olewiler, and Forsdyke, 2002 Cu 1: Cho MNPB = 1000-10Q v MEC = 10Q. Gi s c sn xut mt n v sn phm th to ra mt n v nhim. Hy xc nh mc nhim ti u di dng thit hi hoc chi ph ngoi ng. (1) Khi lng sn phm ti u l Q* tho mn iu kin cn bng cn bin. MNPB = MEC 1000 -10Q = 10Q Q* = 50 Mc nhim ti u tng ng vi mc sn lng Q* = 50 n v sn phm. mc sn lng ny tng thit hi l din tch pha di ng MEC t 0 n Q* hoc tam gic OEQ* bng (50 * 500)/2 = $ 1250.

C,BMEC MNPB

E

O

Q* 50

100

Q/W

Cu hi 5: Xem s di y. N cho thy hai hm MD. MDU v MDR l hm thit hi cn bin ca khu vc thnh th v nng thn mt cch tng ng. MDR = 5ER; MDU = 10EU v MAC = 600 5E Tm hai cn bng hiu qu cho hai hm MD v nhim carbon monoxide. Gi s ngi qun l p dng mt tiu chun ng b mc thi trung bnh cng ca hai mc thi hiu qu. Thit hi qu mc ca khu vc thnh th do kim sot cha mc v ca khu vc nng thn do kim sot qu mc l bao nhiu?$ 600 MAC MDU MDR

0

40

60

120

Lng thi carbon monoxide (kg/thng)

Gi p: Ti mc thi hiu qu x hi, MAC = MD cho mi vng Nng thn: MAC = MDR Thnh th : MAC = MDU 5ER = 600 5ER 10EU = 600 5EU E*R = 60 E*U = 40 MACR (60) = 300 MACU (40) = 400 Tiu chun c t mc 50 lng thi l trung bnh cng ca hai mc thi hiu qu x hi: MAC (50) = 350 MDR (50) = 250 MDU (50) = 500 Thay i ca tng thit hi mi vng so vi tng thit hi hiu qu x hi l:

TDR = (250+300) x 10/2 = $2750 (gim)Environmental Economics Teachers Manual 2005

23

TDU = + (400 + 500) x 10/2 = +$4500 (tng)Chng ta c th tnh thng d x hi b mt mi vng bng cch tnh thay i trong tng chi ph x l (TAC). TAC ca khu vc thnh th gim 3750 la trong khi TAC ca khu vc nng thn tng 3250 la. Thng d x hi b mt khu vc thnh th v nng thn do tiu chun ng b l 750 la v 500 la mt cch tng ng.

Cu 4: S dng s di y v phng trnh MAC1 = 200 5E v MAC2 = 160 4E, hy tnh chi ph tit kim c ca ch th gy nhim nu p dng cng ngh mi (MAC2) sau khi ban hnh thu thi 100 la mi tn. Hy tnh chi ph tit kim c khi p dng tiu chun 20 tn. Gii thch ti sao thu em li khuyn khch ci tin ln hn so vi tiu chun.$ 200 160 Thu =100 mi tn e 0 15 d 20MAC1 MAC2

c a b 40 Pht thi (tn mi nm)

Gii p:

Hng s x l n mc MAC bng thu sut, vt qu im , np thu l tit kim chi ph hn x l. Vi cng ngh c, hng s x l 20 tn cht thi. TAC1 = [(40 20) x 100]/2 = 1000 la (din tch a+b) vi cng ngh mi, x l l r hn gy nhim ti mc thi 15 tn. Nh my x l thm 5 tn v tin thu tit kim c l 5 x 100 = 500 la (bng din tch c +d). Nh my x l 15 tn v TAC2 = [(40-15) x100]/2 = $ 1250 (din tch b+d). Tng chi ph tit kim nh cng ngh x l tt hn l TAC1 TAC2 + tin thu tit kim c = $ 250 (din tch a+c). Vi tiu chun 20 tn, tng chi ph TAC vi cng ngh c l 1000 la (din tch a+b), v vi cng ngh mi l [(80 x (40 200)]/2 = 800 la (din tch b). Tng chi ph tit kim c l 200 la, s khc bit ca TAC (din tch a). Chi ph tit kim thm c l 50 la tin thu. Thu em li khuyn khch ci tin ln hn bi v ng MAC gim xung tng i so vi thu sut khuyn khch nh my gim nhim trnh thu. Khi p dng tiu chun, nh my khng linh hot nh vy bi v lng pht thi ti a l c nh. Cu 4. Hai nh my gy nhim c th kim sot/x l nhim ca mt cht no c MAC nh sau: MAC1 = $300 10 E1 v MAC2 = $90 5 E1 Ga s mc nhim mc tiu l 30 n v. Chng ta khng bit c phi l mc hiu qu x hi hay khng. (a) Hy tnh mc thi ca mi nh my t hiu qu chi ph x hi.Environmental Economics Teachers Manual 2005

27 (b) Gii thch h thng giy php thi c th chuyn nhng c th p dng nh th no t c mc thi mc tiu. Gi s khi bt u ngi qun l cp min ph 15 giy php cho mi ch th gy nhim. Tm s lng giy php m mi nh my gi khi th trng giy php hot ng, gi ca giy php, v tng chi ph t nhn ca h thng giy php. Chi ph t nhn ca mi nh my s thay i nh th no nu t u nh nc bn u gi giy php cho cc ch th gy nhim? Gii p: (a) Mc tiu l E1 +E2 = 30 n v (1). x l l hiu qu chi ph: MAC1 =MAC2 (2) T (1) & (2) ta c: E1 =24 v E2 =6 (b) Nu nh qun l cp 15 giy php cho mi nh my. MAC1 = MAC2 = gi giy php khi nh my 1 gi 24 giy php v nh my 2 gi 6 giy php. C ngha nh my 1 mua 9 giy php t nh my hai. Trc khi trao i: Sau khi trao i: TAC 1 = [(30-15) x150]/2 = $1125 TAC 2 = [(18-15) x15]/2 = $22.5 TAC 1 = [(30-15) x60]/2 = $180 TAC 2 = [(18-6) x60]/2 = $360 Chn (9) giy php c mua bn vi gi tr: 60 la x 9 = 540 la (gi s tt c cc giy php u bn gi cn bng). Chi ph c nhn tit kim c do trao i l: Nh my 1: TAC01 TAC1 1 chi ph mua giy php = 1125 180 540 = 405 la Nh my 2: TAC la0 2 1 1 0 0

TAC

1

2

+ doanh thu giy php = 22.5 360 + 540 = 202.5

Tng chi ph tit kim c nu lc u giy php c cp min ph l 607,5 la. Nu giy php c bn u gi, mi nh my b thit mt khon bng gi tr giy php c cp min ph ban u 900 la, tng chi ph ca c hai nh my tng thm 1800 la. Cu 5. Cng c chnh sch no trong s cc cng c: tiu chun ng b, tiu chun c nhn, thu thi, hoc giy php nhim c th chuyn nhng to khuyn khch ln nht i vi u t nghin cu pht trin h thp chi ph x l? Hy chng minh bng th. Gii p: TDPs (trong iu kin cnh tranh) v thu to khuyn khch ci tin ngang bng vi tiu chun c nhn. Xem s di y.


28

$/tn MAC (trc ci tin)

P* = t*

c d aE1

b

MAC (sau ci tin) Pht thi (tn)

0

E2

Khi tiu chun c nhn t ti E1, nu nh my ci tin, tit kim ca nh my nh gim tng chi ph x l l din tch (a+b) a = b. Khi thu sut c nh l t*, n khin nh my x l n E2, tng chi ph x l l din tch (a+d) v tit kim c (c+d) v tin thu. Tit kim rng khi l (a+b) (a+d) + (c+d) = b+c. Vi h thng TDP, tng chi ph xa l ban u ca nh my l nh trng hp thu l (a+b). Nu nh my ci tin chi ph x l cn bin s thp hn so vi tr tin mua giy php cho tt c cc mc thi ln hn E2 v vy nh my bn (E1- E2) giy php. Tng chi ph x l mi TAC khi l (a+d) v doanh thu giy php l (c+d). Tit kim nh ci tin l (a+b) (a+d) + (c+d) = (c+b). Tit kim ging nh trng hp thu. Nu th trng giy php l khng cnh tranh hon ho tt c li ch c thm t trao i c thc hin, khi thu to nn li ch tng thm t ci tin ln hn so vi h thng TDP. V d, nh my l khch hng ln th trng giy php cho nn bn ht mt s lng ln giy php s lm cho gi giy php gim xung. Li ch tng thm nh ci tin s gim khi gi giy php gim. Cng nh vy, bn ht giy php c th gy tr ngi cho n lc ca nh my gi giy php lm ro cn s tham gia ca nhng nh my cng cnh tranh trn mt th trng hng ho. Cnh tranh tng ln c th nh hng li ch c thm c t ci tin bi v li nhun ca nh my gim do gi hng ho gim v gi u vo tng. Mt yu t khc c th tip tc lm gim khuyn khch ci tin khi p dng tiu chun l tim nng c quan qun l tng tnh nghim ngt ca tiu chun sau khi c ci tin. Bi tp 1: Ph vo cng Rng quc gia Cc Phng l 10 la/ngi cho mt ngy tham quan. Nu hng ngy ng cu gii tr ti cng vin cho trc l Q = 40 1/2P, th thng d tiu dng ca khch tham quan n cng vin s l 1225 la /ngy. ng hay sai? Gii thch cu tr li. Bi gii: ng. Bng cch tnh ng cu o ngc (P = 80 - 2Q) v ly din tch vng tam gic di ng cu v trn ng P =10, bn c th xc nhn rng thng d ngi tiu dng qu tht l 1225 la/ngy. Nu bn v ng mt bc tranh nhng trnh by cch tnh ton sai, bn mt i 6 im. Lu rng ng cung khng thch hp cho mc ch tnh thng d tiu dng ngi tiu dng trong trng hp ny ch n gin i mt vi gi c chnh ph n nh, c th hay khng th phn nh chi ph cung ng cc dch v cng vin. Bi tp 2: Cho bn s liu kho st sau y v nhng ngi i b ng di trn ng mn Bruce (Bruce Trail) on ng Chi ph Dn s (n v S ngy T l Chi ph i (km) du hnh ($) 1000) chy b tham quan du hnh 0-50 25.000 500 20.000 51-100 50.000 2500 75.000 101-150 75.000 5000 100.000 151-200 100.000 3000 30.000 (a) V th ng cu chy b trn Bruce Trail (b) Vit v v phng trnh ng thng t d liu bn c. (c) Tnh tng li ch t chuyn i Bruce Trail bng thng tin c dn ca cc vng bo co. (d) Gi thit ngi xa Bruce Trail c thm ng chy thay th gn . iu ny lm sai lch tng li ch c tnh ca Bruce Trail nh th no? Bi gii: Tnh tng li ch ca ng Bruce i vi c dn cc vng

on ng i (km) 0-50 51-100 101-150 151-200

Giao im gia ng cu v trc tung 125 125 125 125

Chi ph du hnh ($) 25.000 50.000 75.000 100.000 125,000

Thng d tiu dng (CS/1000) ($) 2.000 1.125 500 125 0 Total CS =

Tng CS ($) 1.000.000 2.812.500 2.500.000 375.000 0 6.687.500


38 Nu ngi s dng on ng c thm ng thay th, lng cu ca h mc gi cao s thp hn lng cu mc gi thp. Giao im gia ng cu v trc tung s b c lng thp hn mc thc t. Li ch ca c dn gn s b c lng thp hn mc thc t. CH 5: Phng php gi c hng th Cu hi 1: Mt cng nhn tiu biu cho mi kha cnh, lm vic vi tin lng 40.000$ mt nm trong cho mt ch lm hon ton an ton. Mt cng nhn in hnh khc lm mt cng vic i hi cng nhng k nng tng t, nhng mt ch lm y ri ro c th dn n ci cht xc sut 1 trong 1000 ngi hng nm, v nhn mc lng 44.000$ mt nm. Gi tr ca i ngi ca cc cng nhn vi nhng c im ny l bao nhiu nn dng phn tch chi ph -li ch. Gii p : Cc cng nhn i hi 4.000$ chp nhn ri ro t vong vi xc sut 0.001. Gi tr i ngi p ch bng con s 4.000$/0,001 = 4.000.000$. Bi tp 1: Chi ph ting n. Gi s mi ngi s hu cc cn h ging nhau gn sn bay. Nu mt tuyn ng bng mi c xy dng, cc cn h trong vng A s hng gi tr li ch v h cm thy yn tnh hn. Nhng cc cn h vng B, nm di ng bay mi, mt i gi tr v h cm thy n o hn. Bng s liu di y cung cp s cn h v nhng thay i trong gi tr mi vng. Hon tt cc ct bng tay tnh ton nhng thay i trong gi tr vng. Cc cn h Gi tr 1000 la S cn h Thay i (gi tr tin $) Trc Sau A Yn tnh hn 250 280 10.000 ? B n o hn 250 210 5.000 ? a. Li ch, chi ph v li ch rng t nhng thay i l bao nhiu ? b. n gin, gi thit nhng thay i trong ting n l ngun li ch hay chi ph duy nht. ng bng mi v ci thin Pareto thc t theo nhng iu kin no? Mt ci thin Pareto tim nng ? Gii p : Cc cn h

Gi tr $000 S h Thay i $m Trc Sau A Yn tnh hn 250 280 10.000 +300 B n o hn 250 210 5.000 200 a. Li ch, chi ph v li ch rng ln lt l $300m, $200m, v $100m. b. ng bng mi l s ci thin Pareto thc t nu ngi hng li (A) b p cho ngi tn tht (B). l ci thin Pareto tim nng nu ngi hng li khng n b cho ngi tn tht.Environmental Economics Teachers Manual 2005

39 Bi tp 2: Li ch ca ng dn nc. Li ch lp t mt ng dn nc mi n nng tri s nm trong gi c thm vo m ngi mua s tr cho nng tri c ng ng dn nc. Mt s nng tri huyn c sn ng dn nc v mt s nng tri th khng c. Mt cuc kho st v phn tch nhng nng tri ny cho kt qu mt m hnh hng th sau y lin quan n gi c tr cho nhng c im ca cc nng tri. Gi tr khu t = 500 + 200 SCHEME 0.2 AREA + 1.8 RAIN Trong : kch thc trung bnh ti sn (AREA) huyn l 1.000 ha v lng nc trung bnh (RAIN) l 150 mm, v gi tr khu t l la /ha. SCHEME c nh ngha l 1 nu c chng trnh ng dn nc, v 0 = khng c ng dn nc. Tnh li ch ca chng trnh vi gi c hng th, bng qui trnh sau y. a. a gi tr trung bnh ca AREA v RAIN vo phng trnh, v din t li n nh sau: Gi tr khu t = Hng s + 200 SCHEME b. Tnh ton gi tr khu t trn 1 ha khi c v khng c chng trnh. Gi tr tng ln ca mi ha l bao nhiu, vi chng trnh ng dn nc? c. Tnh s gia tng trong gi tr mi ti sn, vi chng trnh ng dn nc. Gii p: Li ch tnh nh sau: a. M hnh: Gi tr khu t = 500 + 200 SCHEME -0,2(1000) + 1,8(150) = 500 + 200 SCHEME 200 + 270 = 570 + 200 SCHEME b. Khng c chng trnh: gi tr khu t trn mt ha = 570 + 200*0 = $570 C chng trnh: gi tr khu t trn mt ha = 570 + 200*1 = $770 Tng gi tr cho mi ha c chng trnh l $200 c. Tng gi tr ti sn = tng gi tr cho mi ha t x 1000 = 200 x 1000 = $200.000 Cu hi 2. Gi s chnh quyn thnh ph ang c gng tm cch gii quyt vn nhim do thuc tr su i vi ngun cung cp nc cho thnh ph. Chnh quyn thnh ph mun tin hnh mt phn tch li ch chi ph vi hai phng n kim sot thuc tr su khc nhau: Nng cp nh my x l nc thi th loi b thuc tr su, hoc Cm s dng thuc tr su trong phm vi thnh ph.

Gi s cch no cng gim thuc tr su n mt mc khng nh hng bt li sc khe con ngi. Chi ph ca cc phng n kim sot ny nh sau:


43 Nng cp nh my x l nc thi th: Chi ph vn = $20 triu. Nh my mi c xy dng trong nm th nht v bt u hot ng vo cui nm (th nht) ny. Khi nh my bt u hot ng, chi ph hot ng l $1 triu mt nm. Thi gian hot ng ca nh my ko di 5 nm, v sau phi c thay bng mt nh my mi. Cm dng thuc tr su: Chi ph hot ng hng nm do thay th cc phng php khng c hi kim sot su bnh l $3.5 triu mi nm.

-

Cho sut chit khu l 5%, v thi gian thc hin k hoch ca thnh ph l 10 nm. Gi s NPV ca li ch ca d n l $40 triu. Chnh quyn thnh ph nn chn phng n no? By gi gi s mi phng n x l c cc li ch khc nhau. C th, hin gi vn l $40 triu i vi phng n cm dng thuc tr su, nhng c th c cc li ch tng thm di dng t thit hi hn i vi h sinh thi so vi phng n nng cp nh my x l nc thi. Mc chnh lch cc li ch tng thm ny phi l bao nhiu mi nm chnh quyn thnh ph bng quan gia phng n nng cp nh my x l nc thi v phng n cm dng thuc tr su? Tr li: Tt c cc con s tnh theo triu la. Hin gi (PV) c tnh bng cch chia gi tr hin t hnh (CV) cho (1 + r) , y t l thi gian v r l li sut. Chi ph nng cp nh my x l cht thi th: 0 CV chi ph hot ng PV chi ph hot ng CV chi ph vn PV chi ph vn20 209

11 0.95

21 0.91

31 0.86

41 0.82

51 0.78 20 15.7

61 0.75

71 0.71

81 0.68

91 0.65

Tng chi ph9 7.11 40 35.67

PV (chi ph hot ng) = 1 triu (1-1/(1 + r) )/r=7.11 PV (li ch rng) = PV (li ch) PV (chi ph) = 40 42.78 = -2.78 (triu) Chi ph cm dng thuc tr su 0 CV chi ph hot ng PV chi ph hot 3.5 3.5 1 3.5 3.3 2 3.5 3.2 3 3.5 3.0 4 3.5 2.9 5 3.5 2.7 6 3.5 2.6 7 3.5 2.5 8 3.5 2.4 9 3.5 2.3 Tng chi ph 35.0 28.4


44 ng 10 PV (chi ph hot ng) = 3.5 triu (1-1/(1 + r) )(1 + r)/r PV (li ch rng) = 40 28.38 = 11.62 (triu) Cm dng thuc tr su c hin gi cao hn. Nu nng cp nh my x l nc thi th cho hin gi li ch cao hn trong khi cm dng thuc tr su vn cho hin gi li ch l $40 (triu), bng quan gia cc d n, th PV ca li ch rng phi bng nhau gia cc d n. Hin gi ca li ch rng i vi phng n nng cp nh my x l nc thi th phi l $54.40 (triu). Cu hi 3. B giao thng (MOT) ang xem xt liu c nn u t vo mt ng hm mi qua ni ( y hin c mt con ng qua ni) hay khng. MOT chi $3 triu (theo gi nm 2000) cho vic nghin cu kh thi v nhn thy rng ng hm mi c th gim thi gian lu thng cho gn 200,000 ngi. Mt phn tch gn y ch ra rng ng hm c th tit kim khong 33 gi i li hng nm cho mt ngi. Mt nghin cu tin hnh nm 1992 cho thy nhng ngi i li hng ngy nh gi gi tr thi gian ca h khong $11 mt gi (theo gi nm 1990). Bn c th gi s gi tr thc ca thi gian i li khng i. ng hm c th tn chi ph xy dng $1 t (theo gi nm 2000) v mt 6 nm mi hon thnh. Mt khi d n hon thnh, chi ph vn hnh v bo tr ng hm l $25 triu mt nm (theo gi nm 2000). Chi ph thc c tin rng s khng i theo thi gian. MOT ng ti tr chi ph xy dng ban u, nhng chi ph vn hnh v bo tr phi c hon tr bng tin thu ph. 1. i vi mi quan im, nhn dng mi mc trong bng s c tnh l li ch (B), chi ph (C) hay khng (NC) trong vic xc nh li ch rng ca d n. MOT Ngi s dng ng hm X hi Nghin cu kh thi NC NC NC Tit kim thi gian NC B B Chi ph xy dng C NC C Chi ph vn hnh v bo tr C NC C Tr cp B NC or C* NC Tin thu ph B C NC * Bn c th lp lun rng ngi s dng ng hm c th s tr khon tr cp thng qua thu cao hn. 2. Mt s n gin ha trong phn tch gii hn chnh xc ca vic nh gi l g? + Gi tr thc ca thi gian i li c th tng hoc gim theo thi gian. + S lng ngi s dng ng hm c th tng hoc gim theo thi gian. + Chi ph thc ca vic vn hnh v bo tr c th tng hoc gim theo thi gian. 3. Cc li ch v chi ph c th c khc m chng ta nn xem xt trong nh gi li ch rng l g? + M ng hm c th thu ht nhiu ngi i li bng ng hm thay v i bng cc phng tin giao thng khc lm gim kt xe trn cc ng cao tc, gim nhim khng kh, + Chi ph hiu qu do tng thu tr cp xy ng hm mi.Environmental Economics Teachers Manual 2005

45 + Chi ph thi gian i vi nhng ngi i li hng ngy do tr hon trong sut thi gian xy ng hm. 4. Theo quan im x hi, hin gi ca chi ph ca d n theo gi nm 2000 l bao nhiu nu vng i d n l 30 nm v sut chit khu hng nm l 3%? S dng tha s chit khu dng tin u tnh ton cu tr li ca bn v gi s cc khon thanh ton c tnh u mi giai on. PV ca chi ph vn hnh v bo tr u nm 7/cui nm 6 tnh bng triu la theo gi nm 2000: c tha s chit khu dng tin u ca khon tr trc cho 24 nm, chng ta s dng gi tr ca tha s chit khu dng tiu u cho khon tin cho 23 nm vi sut chit khu 3%, 16.4436, v cng 1: PV ( 25 )(17.4436 ) 436.09 + 1 1(1+r ) = E1n

436.09

r

PV ca chi ph vn hnh v bo tr u nm 1 (triu la theo gi nm 2000): PV

3656 1.03 PV ca chi ph xy dng u nm 1 (theo gi nm 2000): $1 t Tng chi ph theo gi nm 2000: $1.365 t 5. Theo quan im x hi, hin gi ca li ch ca d n theo gi nm 2000 l bao nhiu nu vng i d n l 30 nm v sut chit khu l 3%? (Lu : S dng CPI trong phn ghi ch bi ging). Li s dng tha s chit khu dng tin u tnh ton cu tr li ca bn nhng n gin, gi nh rng cc li ch pht sinh tnh cui nm. Gi tr thi gian mt ngi theo gi nm 2000:1 CPI V2000 = V1990 CPI = 11 72.8 14.54 130.72000 1990

Li ch hng nm nh tit kim thi gian theo gi nm 2000:

( $14.54

hour

)( 33 hours commuter ) ( 200,000 commuters year )

$95.96million

PV ca li ch tit kim thi gian tnh bng triu la theo gi nm 2000 u nm 7/cui nm 6: V chng ta gi nh cc li ch pht sinh tnh vo thi im cui giai on, nn chng ta s dng gi tr ca tha s chit khu dng tin u cho 24 nm vi sut chit khu l 3%, 16.9355 .1 PV 95.96 16.9355 1, 625.2 =E +r 1 (n ) r


46 PV ca li ch tit kim thi gian tnh theo triu la theo gi nm 2000 thi im bt u nm 1: PV 1, 625.2 1, 361 6 1.03

Tng li ch tnh theo gi nm 2000: $1.361 billion 6. Hin gi ca li ch rng theo gi nm 2000 l bao nhiu? Li ch rng = PV li ch PV chi ph = $1.361 t - $1.365 t = - $4 triu

CH 1: Gii thiu v li ch ca ti nguyn thin nhin, quyn ti sn, t, vgi tr ca t Cu hi 1: Gi s anh/ch d nh mua mt m vng. Chi ph hng nm xy dng m l 1 triu trong ba nm, c th khai thc vng vo nm th 4. Mi nm hot ng thu nhp rng (tng doanh thu tr tng chi ph) l 800.000 la. Anh/ch s tr gi bao nhiu cho m vng nu: a) Mc chit khu l 10% v vng c th khai thc trong vng 10 nm? b) Mc chit khu l 5% v c th khai thc vng trong vng 6 nm? Gii p: a) 3 - $1.000.000 13 $800.000 NPV = ------------------ + -------------= $1.206.351 i i i=1 (1+0,10) i=4 (1+0,10) b) 3 - $1.000.000 9 $800.000 NPV = ------------------ + -------------- = $784.411 i i i=1 (1+0,05) i=4 (1+0,05) Bi tp: Nm 2002, Cng ty Unocal khm ph ra mt m kh t nhin vi tr lng c tnh khong 71 t tn vng bin ty nam Vit Nam. Hin ti Unocal ang chun b k hoch kh thi khai thc m kh trong hai thi k. Chi ph khai thc, bao gm chi ph lp t gin khoan, h thng ng ng, v chi ph hot ng, c tnh khong 200 USD mi tn. Chi ph khai thc cn bin gi s l khng i. ng cu sn phm kh trong hai thi k l P = 1200 23Q , vi n v o lng ca P l USD/triu tn v Q l triu tn. Sut chit khu l 10% /thi k. a) Tnh tc khai thc ti u cho mi thi k. b) Gi s nh nc quyt nh nh thu ti nguyn. Thu sut l 50 USD/tn. Hy tnh li kt qu ca cu hi a. c) Gi nh khi ph duyt d n Unocal, chnh ph thc hin mt iu tra khc nh gi tr lng mt ln na v khm ph ra rng tr lng kh t nhin by gi l 82 t tn. Vi thu sut 50 USD/tn, tnh ton tc khai thc ti u cho mi thi k.

Gii p bi tp 1: a) S dng nguyn tc Hotelling cho m hnh hai giai on: P P c= 1 c 0 1+ r P0 c = 1200 23Q0 200 = 1000 23Q0 P1 c 1200 23Q1 200 1000 23Q1 = = = 909 20.9Q 1 1+ 1+ 1.1 r 10% Rng buc: Q0 + Q1 = 71, hoc: Q1 = 71 Q0 P c P c= 1 1000 = 909 20.9Q1 23Q 0 1+r 1000 23Q0 = 909 20.9(71 Q0 )0

1000 23Q0 = 909 1483.9 + 20.9Q0 1000 909 + 1483.9 = 23Q0 + 20.9Q0 1574.9 = 43.9Q0 b) P0 c = 1200 23Q0 250 = 950 23Q0 = 863.6 20.9Q 23Q1 1 1+ 1+ 1.1 r 10% Rng buc: Q0 + Q1 = 71, hoc: Q1 = 71 Q0 = =Environmental Economics Teachers Manual 2005

Q0 = 35.87 ; Q1 = 35.13

P1 c

1200 23Q1 200

950

51 P1 c = 863.6 20.9Q10

P c=0

950

23Q 1+r

950 23Q0 = 863.6 20.9(71 Q0 ) 950 23Q0 = 863.6 1483.9 + 20.9Q0 950 863.6 + 1483.9 = 23Q0 + 20.9Q0 1570.3 = 43.9Q0 c) Q1 = 82 Q0 950 23Q0 = 863.6 20.9(82 Q0 ) 950 23Q0 = 863.6 1713.8 + 20.9Q0 950 863.6 + 1713.8 = 23Q0 + 20.9Q0 1800.2 = 43.9Q0 Q0 = 41.02 ; Q1 = 40.98 Q0 = 35.77 ; Q1 = 35.23

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