ECON7070, 2021 Practice Test 2
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ECON7070, 2021
Practice Test 2
Test 2 will be a combination of questions like the ones in tutorials 4,5,6 and the following questions.
1 Which is true for the following two-player game:
1 /2 L C R
4 4 |
1, 6 |
4 2 |
6, 0 |
6, 6 |
4 2 |
3, 4 |
5, 9 |
2 2 |
(A) T is a best response to L
(B) (M,C) is the only Nash equilibrium
(C) (M,R) is a Nash equilibrium
(D) There is a mixed strategy Nash equilibrium in which player 2 chooses both C and R with positive probability
The answer is (B)
2 Which is false for the following game?
1 /2 L C R
3, 2 |
0, 3 |
3, 3 |
5, 0 |
4 1 |
3, 1 |
2 2 |
4, 5 |
1 1 |
M
B
(A) (M,C) and (B,C) are the only pure strategy Nash Equilibria
(B) There is a Nash equilibrium in which R is played with positive probability (C) There is no Nash equilibrium in which L is played with positive probability
(D) There is no Nash equilibrium in which both players choose two of their actions with positive probability
The answer is (A)
3 Which is true for the following game?
1 /2 L C R
2, 3 |
3, 4 |
4, 8 |
5, 6 |
4, 3 |
7, 1 |
6, 2 |
5, 5 |
2 4 |
M
B
(A) There is a mixed strategy Nash equilibrium in which Player 1 plays both M and B with
positive probability and Player 2 plays both L and C with positive probability
(B) The best response of Player 2 to M is C
(C) (B,C) is the only Nash equilibrium
(D) (M,L) is a Nash equilibrium
q 1 · q
L R
p 1 · p |
U D |
|
The answer is (C)
4 In the following game, in which s1 = (p, 1 · p) is Player 1’s strategy and s2 = (q, 1 · q) is Player 2’s strategy, Player 1 is indifferent between U and D when q is equal to: [Write you answer as a decimal number, e.g. 0.33]
. The answer is 0.75:
5 In the following game, in which s1 = (p, 1 · p) is Player 1’s strategy and s2 = (q, 1 · q) is Player 2’s strategy, Player 2 is indifferent between L and R when p is equal to: [Write you answer as a decimal number, e.g. 0.33]
q 1 · q
L R
p 1 · p |
U D |
|
. The answer is 0.25:
6 Which is true for the following game?
1 /2 L C R
T
M
B
(A) (T,R) is a Nash equilibrium
(B) There is a Nash equilibrium in which Player 1 plays M and B with equal probability and
Player 2 plays each action L, C and R with positive probability
(C) There is a Nash equilibrium in which Player 1 plays each action T, M and B with positive probability and Player 2 plays each action L, C and R with positive probability
(D) There is a Nash equilibrium in which Player 1 plays M and B with equal probability and Player 2 plays L and C with equal probability
The answer is (D)
7 The following game:
1 /2 L C R
0, 0 |
· 1 1 |
1 · 1 |
|
1 · 1 |
0, 0 |
· 1 |
1 |
· 1 1 |
1 · 1 |
0, |
0 |
(A) Has a pure strategy Nash equilibrium
(B) Has a mixed strategy Nash equilibrium in which Player 1 plays T, M and B with equal
probability and Player 2 plays L C and R with equal probability
(C) Has a mixed strategy equilibrium in which Player 2 only puts positive probability on L and R
(D) Has a mixed strategy Nash equilibrium in which Player 1 plays M and B with probability 0.5 each and Player 2 plays L and C with probability 0.5 each
The answer is (B)
8 If Player 2 chooses L and R with equal probability and Player 3 chooses A and B with equal probability, then Player 1 best response is:
T M D |
L R
A |
T M D |
L R
B |
(A) T
(B) M
(C) D
(D) Both M and D
The answer is (A)
9 In the following game, if Player 2 chooses L and R with equal probability and Player 1 chooses M, then Player 3’s expected utility from choosing A is:
L R L R
T T
M M
D D
A B
The answer is 1
10
Which is false for the following three player game?
T D
3,1,3 |
2,2,3 |
4,4,4 |
1,0,0 |
T
(A) (D,T,T) is a Nash equilibrium
(B) (T,D,D) is a Nash equilibrium
T D
0,3,5 |
4,5,6 |
1,1,1 |
1,2,1 |
D
(C) (T,D,T) is a Nash equilibrium
(D) None of the players has a dominant strategy
● The answer is (C):
11
Which is false for the following game?
1 /2 L R
A
B
C
(A) It has no pure strategy Nash equilibrium
(B) There exists a Nash equilibrium in which player 1 plays B with zero probability (C) There exists a Nash equilibrium in which player 1 plays C with zero probability
(D) There exists a Nash equilibrium in which player 1 plays A with zero probability
● The answer is (B)
12 Let s1 = (pT , pM , pB ) be the strategy of Player 1 (with pi the probability of action i) and s2 = (qL , qC , qR ) be the strategy of Player 2 (with qi the probability of action i). Which is false for the following game?
L C R
0, 0 |
3, 3 |
0, · 1 |
1, 1 |
0, 0 |
3, ·2 |
0.5, 2 |
1, 5 |
0, 1 |
(A) (M,L) and (T,C) are the only pure strategy Nash equilibria
(B) s1 = (0.5, 0.5, 0) and s2 = (0.5, 0.5, 0) is a Nash equilibrium
(C) s1 = (0.25, 0.75, 0) and s2 = (0.75, 0.25, 0) is a Nash equilibrium
(D) In any strictly mixed strategy equilibrium, Player 1 puts positive probability on T and M only, and Player 2 puts positive probability on L and C only
The answer is (B):
13 Consider a simultaneous move game played by two players, Player 1 and 2. Player i’s action set is ti e [0, o) and the utility function of player i is
.·ti
ui(t1 , t2 ) = .0.5vi · ti .(vi · tj
if ti < tj
if ti = tj
if ti > tj
where i j and v1 = 20, v2 = 10. Which of the following is not a pure strategy Nash equilibrium of this game?
(A) (t1(*), t2(*)) = (0, 20)
(B) (t1(*), t2(*)) = (10, 0)
(C) (t1(*), t2(*)) = (10, 20)
(D) (t1(*), t2(*)) = (0, 30)
The answer is (C)
14 Consider a Cournot duopoly. The market demand function is P = 130 · (q1 + q2 ), where P is the market price, q1 is the output produced by Firm 1 and q2 is the output produced by Firm 2. The two firms have a constant marginal cost c = 10. The pure strategy Nash equilibrium of this game is:
(A) (q1(*), q2(*)) = (20, 20)
(B) (q1(*), q2(*)) = (10, 10)
(C) (q1(*), q2(*)) = (30, 30)
(D) (q1(*), q2(*)) = (40, 40)
The answer is (D)
15 Consider a Cournot duopoly. The market demand function is P = 130 · (q1 + q2 ), where P is the market price, q1 is the output produced by Firm 1 and q2 is the output produced by Firm
2. Firms 1 have a constant marginal cost of c1 = 10, while Firm 2 has a constant marginal cost of c2 = 40. Which is false?
(A) Firm 1 best response function is: q1 = max{60 · 0.5q2 , 0}
(B) Firm 2 best response function is: q2 = max{45 · 0.5q1 , 0}
(C) (q1(*), q2(*)) = (60, 0) is a Nash equilibrium
(D) (q1(*), q2(*)) = (50, 20) is a Nash equilibrium
The answer is (C)
2023-01-03