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September 2024 term · Game Theory and Strategy · BSMS4023

Game Theory and Strategy Quiz 2: 1 December 2024 (September 2024 term)

The IIT Madras BS Game Theory and Strategy (Game Theory) Quiz 2 paper sat on 1 Dec 2024, in the September 2024 term: 25 questions for 25 marks in 120 minutes. Every question is below with its answer. Take it as a timed mock test to be marked, or read it through first.

Questions
25
Marks
25
Duration
120 min
MCQ
17
Numerical
8

Updated

Official paper: IIT M DEGREE AN EXAM QDB2 01 Dec 2024 · No negative marking.

Question 1

+1 markOne correct option

Consider the example of cascade discussed in the lecture but with a modification that now the urn is containing either 4 blue balls and 1 red ball or 4 red balls and 1 blue ball with equal probability. That simply means that the urn is equally likely to be blue-majority urn or red-majority urn. We assume everyone hears what the previous individuals report and get their own private signal by randomly drawing one ball from the urn.
Based on the above data answer the given subquestions.

Suppose one ball is picked from the blue majority urn. What is the probability that the ball is blue?

  1. A

    1/4

  2. B

    3/4

  3. C

    1/5

  4. D

    4/5

Show answer

Correct answer

  • D

    4/5

Question 2

+2 marksOne correct option

Consider the example of cascade discussed in the lecture but with a modification that now the urn is containing either 4 blue balls and 1 red ball or 4 red balls and 1 blue ball with equal probability. That simply means that the urn is equally likely to be blue-majority urn or red-majority urn. We assume everyone hears what the previous individuals report and get their own private signal by randomly drawing one ball from the urn.
Based on the above data answer the given subquestions.

What is the probability that the urn is blue-majority if the first student draws a red ball?

  1. A

    1/5

  2. B

    4/5

  3. C

    3/4

  4. D

    1/4

Show answer

Correct answer

  • A

    1/5

Question 3

+1 markOne correct option

Consider the example of cascade discussed in the lecture but with a modification that now the urn is containing either 4 blue balls and 1 red ball or 4 red balls and 1 blue ball with equal probability. That simply means that the urn is equally likely to be blue-majority urn or red-majority urn. We assume everyone hears what the previous individuals report and get their own private signal by randomly drawing one ball from the urn.
Based on the above data answer the given subquestions.

Now suppose, first three students draw the ball in the sequence (Blue, Blue, Red).
What is the probability of getting this sequence if the urn is a blue-majority urn?

  1. A

    3/64

  2. B

    4/125

  3. C

    16/125

  4. D

    9/125

Show answer

Correct answer

  • C

    16/125

Question 4

+1 markOne correct option

Consider the example of cascade discussed in the lecture but with a modification that now the urn is containing either 4 blue balls and 1 red ball or 4 red balls and 1 blue ball with equal probability. That simply means that the urn is equally likely to be blue-majority urn or red-majority urn. We assume everyone hears what the previous individuals report and get their own private signal by randomly drawing one ball from the urn.
Based on the above data answer the given subquestions.

Now suppose, first three students draw the ball in the sequence (Blue, Blue, Red).
What is the probability of getting this sequence if the urn is a red-majority urn?

  1. A

    3/64

  2. B

    9/125

  3. C

    16/125

  4. D

    4/125

Show answer

Correct answer

  • D

    4/125

Question 5

+1 markOne correct option

Consider the example of cascade discussed in the lecture but with a modification that now the urn is containing either 4 blue balls and 1 red ball or 4 red balls and 1 blue ball with equal probability. That simply means that the urn is equally likely to be blue-majority urn or red-majority urn. We assume everyone hears what the previous individuals report and get their own private signal by randomly drawing one ball from the urn.
Based on the above data answer the given subquestions.

Now suppose, first three students draw the ball in the sequence (Blue, Blue, Red).
What is the total probability of getting this sequence?

  1. A

    2/25

  2. B

    9/25

  3. C

    6/125

  4. D

    3/125

Show answer

Correct answer

  • A

    2/25

Question 6

+2 marksOne correct option

Consider the example of cascade discussed in the lecture but with a modification that now the urn is containing either 4 blue balls and 1 red ball or 4 red balls and 1 blue ball with equal probability. That simply means that the urn is equally likely to be blue-majority urn or red-majority urn. We assume everyone hears what the previous individuals report and get their own private signal by randomly drawing one ball from the urn.
Based on the above data answer the given subquestions.

Now suppose, first three students draw the ball in the sequence (Blue, Blue, Red).
What is the probability of urn being red-majority in this scenario?

  1. A

    3/25

  2. B

    1/5

  3. C

    4/5

  4. D

    9/25

Show answer

Correct answer

  • B

    1/5

Question 7

+1 markOne correct option

If player 1 chooses 1.5 hour as his action, the best response of player 2 will be

  1. A

    1.5

  2. B

    1

  3. C

    1.25

  4. D

    0

Show answer

Correct answer

  • C

    1.25

Question 8

+1 markOne correct option

How much negative campaign time each player will choose under a symmetric and unique Nash equilibrium?

  1. A

    1.5

  2. B

    1

  3. C

    1.25

  4. D

    0

Show answer

Correct answer

  • B

    1

Question 9

+1 markOne correct option

Equilibrium payoff of each player will be

  1. A

    -1.5

  2. B

    1

  3. C

    -1

  4. D

    0

Show answer

Correct answer

  • C

    -1

Question 10

+1 markOne correct option

Now assume that this game is repeated infinitely. If the parties cooperate and sign a binding agreement on how much to campaign, they choose a1 = a2 = 0.
What will be the payoff of each player in each stage game if they stick to this agreement

  1. A

    -1.5

  2. B

    1

  3. C

    -1

  4. D

    0

Show answer

Correct answer

  • D

    0

Question 11

+2 marksOne correct option

Now assume that this game is repeated infinitely. If the parties cooperate and sign a binding agreement on how much to campaign, they choose a1 = a2 = 0.

  1. A

    1

  2. B

    1/2

  3. C

    1/3

  4. D

    1/4

Show answer

Correct answer

  • B

    1/2

Question 12

+2 marksOne correct option

Now assume that this game is repeated infinitely. If the parties cooperate and sign a binding agreement on how much to campaign, they choose a1 = a2 = 0.

  1. A
  2. B
  3. C
  4. D
Show answer

Correct answer

  • B

Question 13

+1 markOne correct option

Given the following preference structure, find a stable matching system using the Gale–Shapley algorithm, when the women propose:

Based on the above data answer the given subquestions.

Mr. a will be paired with

  1. A

    A

  2. B

    B

  3. C

    C

  4. D

    None

Show answer

Correct answer

  • D

    None

Question 14

+1 markOne correct option

Given the following preference structure, find a stable matching system using the Gale–Shapley algorithm, when the women propose:

Based on the above data answer the given subquestions.

Mr. b will be paired with

  1. A

    A

  2. B

    B

  3. C

    C

  4. D

    None

Show answer

Correct answer

  • C

    C

Question 15

+1 markOne correct option

Given the following preference structure, find a stable matching system using the Gale–Shapley algorithm, when the women propose:

Based on the above data answer the given subquestions.

Mr. c will be paired with

  1. A

    A

  2. B

    B

  3. C

    C

  4. D

    None

Show answer

Correct answer

  • B

    B

Question 16

+1 markOne correct option

Given the following preference structure, find a stable matching system using the Gale–Shapley algorithm, when the women propose:

Based on the above data answer the given subquestions.

Mr. d will be paired with

  1. A

    A

  2. B

    B

  3. C

    C

  4. D

    None

Show answer

Correct answer

  • A

    A

Question 17

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of a = ___________

Show answer

Correct answer: 3

Question 18

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of b = ___________

Show answer

Correct answer: 1

Question 19

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of c = ___________

Show answer

Correct answer: 2

Question 20

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of d = ___________.

Show answer

Correct answer: 0

Question 21

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of p = ___________

Show answer

Correct answer: 0

Question 22

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of q = ___________

Show answer

Correct answer: 0.67 (accepted within ±0.01)

Question 23

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of r = ___________

Show answer

Correct answer: 0.335 (accepted within ±0.005)

Question 24

+0.5 marksNumerical answer

(Bayesian Game) Consider a variant of the situation modelled by Battle of Sexes (BoS) (as discussed in lectures) in which player 1 is unsure whether player 2 prefers to go out with her or prefers to avoid her, whereas player 2, as before, knows player 1’s preferences. Specifically, suppose player 1 thinks that with probability 1/3 player 2 wants to go out with her, and with probability 2/3 player 2 wants to avoid her. The situation is depicted in the following matrix of a static game with incomplete information:

With the help of this game matrix, we may come up with the following table depicting expected payoff of player 1 corresponding to different actions of both types of player 2.

Based on the above data answer the given subquestions.

Find out the value of t = ___________

Show answer

Correct answer: 1

Question 25

+1 markOne correct option

Consider two statements about Borda count:
I: Borda Count (ignoring ties) always produces a complete, transitive ranking for a set of alternatives.
II: Outcome in Borda count does not depend on the presence of alternatives that seem “irrelevant”.
Choose the correct alternative about these statements:

  1. A

    Only I is true

  2. B

    Only II is true

  3. C

    None is true

  4. D

    Both are true

Show answer

Correct answer

  • A

    Only I is true