CAT 2021 Slot 1 · DILR · Set 3: Friends, Acquaintances and Strangers

The full set and all 6 questions (Q11–Q16) from CAT 2021 Slot 1, with answers and solutions.

Amudha, Bharatan, Chandran, Dhinesh, Ezhil, Fani and Gowtham are seven people in a town. Any pair of them could either be strangers, acquaintances, or friends. All relationships are mutual. For example, if Amudha is a friend of Bharatan, then Bharatan is also a friend of Amudha. Similarly, if Amudha is a stranger to Bharatan, then Bharatan is also a stranger to Amudha.

Partial information about the number of friends, acquaintances, and strangers of each of these people among them is given in the table below.

No. of Friends

No. of Acquaintances

No. of Strangers

Amudha

1

4

Bharatan

Chandran

1

Dhinesh

2

Ezhil

1

Fani

1

Gowtham

3

2

The following additional facts are also known.

1. Amudha, Bharatan, and Chandran are mutual strangers.

2. Amudha, Dhinesh, and Fani are Ezil's friends.

3. Chandran and Gowtham are friends.

4. Every friend of Amudha is an acquaintance of Bharatan, and every acquaintance of Bharatan is a friend of Amudha.

5. Every friend of Bharatan is an acquaintance of Amudha, and every acquaintance of Amudha is a friend of Bharatan.

Question 11 · Caselet DI

Who are Gowtham’s acquaintances?
  1. A
    Dhinesh, Ezhil and Fani
  2. B
    Amudha, Dhinesh and Fani
  3. C
    Bharatan, Dhinesh and Ezhil
  4. D
    Amudha, Bharatan and Fani
Pick an option, then check.
Answer & solution

Answer: Option A

Solving the set

Step 1 – Amudha, Bharatan and Chandran are mutual strangers (fact 1). Amudha has 4 strangers, so besides Bharatan and Chandran she has 2 more strangers, 1 acquaintance and 1 friend (6 relations). Ezhil is her friend (fact 2).

Step 2 – Facts 4 and 5: Amudha's friends = Bharatan's acquaintances, and Amudha's acquaintances = Bharatan's friends. So Ezhil is Bharatan's acquaintance, and Bharatan has exactly one friend (Amudha's single acquaintance).

Step 3 – Chandran–Gowtham are friends (fact 3). Gowtham has 3 acquaintances and 2 strangers, so his only friend is Chandran. Fani has only one friend – Ezhil (fact 2). Ezhil has only one stranger.

Step 4 – Testing who can be Amudha's acquaintance (= Bharatan's friend) among Dhinesh, Fani and Gowtham: Fani's only friend is Ezhil and Gowtham's only friend is Chandran, so it must be Dhinesh. Then Amudha's strangers are Bharatan, Chandran, Fani, Gowtham, and the remaining relations follow from the counts in the table.

Person

Friends

Acquaintances

Strangers

Amudha

Ezhil

Dhinesh

Bharatan, Chandran, Fani, Gowtham

Bharatan

Dhinesh

Ezhil

Amudha, Chandran, Fani, Gowtham

Chandran

Gowtham

Fani

Amudha, Bharatan, Dhinesh, Ezhil

Dhinesh

Bharatan, Ezhil

Amudha, Gowtham

Chandran, Fani

Ezhil

Amudha, Dhinesh, Fani

Bharatan, Gowtham

Chandran

Fani

Ezhil

Chandran, Gowtham

Amudha, Bharatan, Dhinesh

Gowtham

Chandran

Dhinesh, Ezhil, Fani

Amudha, Bharatan

This question

From the relationship table, Gowtham's acquaintances are Dhinesh, Ezhil and Fani.

Hence, the answer is option 1.

Question 12 · Caselet DI

Which of these pairs share the same type of relationship?
  1. A
    (Amudha, Gowtham) and (Ezhil, Fani)
  2. B
    (Bharatan, Chandran) and (Dhinesh, Ezhil)
  3. C
    (Chandran, Ezhil) and (Dhinesh, Gowtham)
  4. D
    (Bharatan, Ezhil) and (Fani, Gowtham)
Pick an option, then check.
Answer & solution

Answer: Option D

Solving the set

Step 1 – Amudha, Bharatan and Chandran are mutual strangers (fact 1). Amudha has 4 strangers, so besides Bharatan and Chandran she has 2 more strangers, 1 acquaintance and 1 friend (6 relations). Ezhil is her friend (fact 2).

Step 2 – Facts 4 and 5: Amudha's friends = Bharatan's acquaintances, and Amudha's acquaintances = Bharatan's friends. So Ezhil is Bharatan's acquaintance, and Bharatan has exactly one friend (Amudha's single acquaintance).

Step 3 – Chandran–Gowtham are friends (fact 3). Gowtham has 3 acquaintances and 2 strangers, so his only friend is Chandran. Fani has only one friend – Ezhil (fact 2). Ezhil has only one stranger.

Step 4 – Testing who can be Amudha's acquaintance (= Bharatan's friend) among Dhinesh, Fani and Gowtham: Fani's only friend is Ezhil and Gowtham's only friend is Chandran, so it must be Dhinesh. Then Amudha's strangers are Bharatan, Chandran, Fani, Gowtham, and the remaining relations follow from the counts in the table.

Person

Friends

Acquaintances

Strangers

Amudha

Ezhil

Dhinesh

Bharatan, Chandran, Fani, Gowtham

Bharatan

Dhinesh

Ezhil

Amudha, Chandran, Fani, Gowtham

Chandran

Gowtham

Fani

Amudha, Bharatan, Dhinesh, Ezhil

Dhinesh

Bharatan, Ezhil

Amudha, Gowtham

Chandran, Fani

Ezhil

Amudha, Dhinesh, Fani

Bharatan, Gowtham

Chandran

Fani

Ezhil

Chandran, Gowtham

Amudha, Bharatan, Dhinesh

Gowtham

Chandran

Dhinesh, Ezhil, Fani

Amudha, Bharatan

This question

• (Amudha, Gowtham) strangers vs (Ezhil, Fani) friends – different.

• (Bharatan, Chandran) strangers vs (Dhinesh, Ezhil) friends – different.

• (Chandran, Ezhil) strangers vs (Dhinesh, Gowtham) acquaintances – different.

• (Bharatan, Ezhil) acquaintances vs (Fani, Gowtham) acquaintances – same.

Hence, the answer is option 4.

Question 13 · Caselet DI

Who is an acquaintance of Amudha?
  1. A
    Dhinesh
  2. B
    Fani
  3. C
    Gowtham
  4. D
    Ezhil
Pick an option, then check.
Answer & solution

Answer: Option A

Solving the set

Step 1 – Amudha, Bharatan and Chandran are mutual strangers (fact 1). Amudha has 4 strangers, so besides Bharatan and Chandran she has 2 more strangers, 1 acquaintance and 1 friend (6 relations). Ezhil is her friend (fact 2).

Step 2 – Facts 4 and 5: Amudha's friends = Bharatan's acquaintances, and Amudha's acquaintances = Bharatan's friends. So Ezhil is Bharatan's acquaintance, and Bharatan has exactly one friend (Amudha's single acquaintance).

Step 3 – Chandran–Gowtham are friends (fact 3). Gowtham has 3 acquaintances and 2 strangers, so his only friend is Chandran. Fani has only one friend – Ezhil (fact 2). Ezhil has only one stranger.

Step 4 – Testing who can be Amudha's acquaintance (= Bharatan's friend) among Dhinesh, Fani and Gowtham: Fani's only friend is Ezhil and Gowtham's only friend is Chandran, so it must be Dhinesh. Then Amudha's strangers are Bharatan, Chandran, Fani, Gowtham, and the remaining relations follow from the counts in the table.

Person

Friends

Acquaintances

Strangers

Amudha

Ezhil

Dhinesh

Bharatan, Chandran, Fani, Gowtham

Bharatan

Dhinesh

Ezhil

Amudha, Chandran, Fani, Gowtham

Chandran

Gowtham

Fani

Amudha, Bharatan, Dhinesh, Ezhil

Dhinesh

Bharatan, Ezhil

Amudha, Gowtham

Chandran, Fani

Ezhil

Amudha, Dhinesh, Fani

Bharatan, Gowtham

Chandran

Fani

Ezhil

Chandran, Gowtham

Amudha, Bharatan, Dhinesh

Gowtham

Chandran

Dhinesh, Ezhil, Fani

Amudha, Bharatan

This question

From Step 4, Amudha's acquaintance is Dhinesh.

Hence, the answer is option 1.

Question 14 · Caselet DI

Who is an acquaintance of Chandran?
  1. A
    Dhinesh
  2. B
    Fani
  3. C
    Ezhil
  4. D
    Bharatan
Pick an option, then check.
Answer & solution

Answer: Option B

Solving the set

Step 1 – Amudha, Bharatan and Chandran are mutual strangers (fact 1). Amudha has 4 strangers, so besides Bharatan and Chandran she has 2 more strangers, 1 acquaintance and 1 friend (6 relations). Ezhil is her friend (fact 2).

Step 2 – Facts 4 and 5: Amudha's friends = Bharatan's acquaintances, and Amudha's acquaintances = Bharatan's friends. So Ezhil is Bharatan's acquaintance, and Bharatan has exactly one friend (Amudha's single acquaintance).

Step 3 – Chandran–Gowtham are friends (fact 3). Gowtham has 3 acquaintances and 2 strangers, so his only friend is Chandran. Fani has only one friend – Ezhil (fact 2). Ezhil has only one stranger.

Step 4 – Testing who can be Amudha's acquaintance (= Bharatan's friend) among Dhinesh, Fani and Gowtham: Fani's only friend is Ezhil and Gowtham's only friend is Chandran, so it must be Dhinesh. Then Amudha's strangers are Bharatan, Chandran, Fani, Gowtham, and the remaining relations follow from the counts in the table.

Person

Friends

Acquaintances

Strangers

Amudha

Ezhil

Dhinesh

Bharatan, Chandran, Fani, Gowtham

Bharatan

Dhinesh

Ezhil

Amudha, Chandran, Fani, Gowtham

Chandran

Gowtham

Fani

Amudha, Bharatan, Dhinesh, Ezhil

Dhinesh

Bharatan, Ezhil

Amudha, Gowtham

Chandran, Fani

Ezhil

Amudha, Dhinesh, Fani

Bharatan, Gowtham

Chandran

Fani

Ezhil

Chandran, Gowtham

Amudha, Bharatan, Dhinesh

Gowtham

Chandran

Dhinesh, Ezhil, Fani

Amudha, Bharatan

This question

From the relationship table, Chandran's acquaintance is Fani.

Hence, the answer is option 2.

Question 15 · Caselet DI

How many friends does Ezhil have?
Answer & solution

Answer: 3

Solving the set

Step 1 – Amudha, Bharatan and Chandran are mutual strangers (fact 1). Amudha has 4 strangers, so besides Bharatan and Chandran she has 2 more strangers, 1 acquaintance and 1 friend (6 relations). Ezhil is her friend (fact 2).

Step 2 – Facts 4 and 5: Amudha's friends = Bharatan's acquaintances, and Amudha's acquaintances = Bharatan's friends. So Ezhil is Bharatan's acquaintance, and Bharatan has exactly one friend (Amudha's single acquaintance).

Step 3 – Chandran–Gowtham are friends (fact 3). Gowtham has 3 acquaintances and 2 strangers, so his only friend is Chandran. Fani has only one friend – Ezhil (fact 2). Ezhil has only one stranger.

Step 4 – Testing who can be Amudha's acquaintance (= Bharatan's friend) among Dhinesh, Fani and Gowtham: Fani's only friend is Ezhil and Gowtham's only friend is Chandran, so it must be Dhinesh. Then Amudha's strangers are Bharatan, Chandran, Fani, Gowtham, and the remaining relations follow from the counts in the table.

Person

Friends

Acquaintances

Strangers

Amudha

Ezhil

Dhinesh

Bharatan, Chandran, Fani, Gowtham

Bharatan

Dhinesh

Ezhil

Amudha, Chandran, Fani, Gowtham

Chandran

Gowtham

Fani

Amudha, Bharatan, Dhinesh, Ezhil

Dhinesh

Bharatan, Ezhil

Amudha, Gowtham

Chandran, Fani

Ezhil

Amudha, Dhinesh, Fani

Bharatan, Gowtham

Chandran

Fani

Ezhil

Chandran, Gowtham

Amudha, Bharatan, Dhinesh

Gowtham

Chandran

Dhinesh, Ezhil, Fani

Amudha, Bharatan

This question

Ezhil's friends are Amudha, Dhinesh and Fani – 3 friends.

Hence, the answer is 3.

Question 16 · Caselet DI

How many people are either a friend or a friend-of-a-friend of Ezhil?
Answer & solution

Answer: 4

Solving the set

Step 1 – Amudha, Bharatan and Chandran are mutual strangers (fact 1). Amudha has 4 strangers, so besides Bharatan and Chandran she has 2 more strangers, 1 acquaintance and 1 friend (6 relations). Ezhil is her friend (fact 2).

Step 2 – Facts 4 and 5: Amudha's friends = Bharatan's acquaintances, and Amudha's acquaintances = Bharatan's friends. So Ezhil is Bharatan's acquaintance, and Bharatan has exactly one friend (Amudha's single acquaintance).

Step 3 – Chandran–Gowtham are friends (fact 3). Gowtham has 3 acquaintances and 2 strangers, so his only friend is Chandran. Fani has only one friend – Ezhil (fact 2). Ezhil has only one stranger.

Step 4 – Testing who can be Amudha's acquaintance (= Bharatan's friend) among Dhinesh, Fani and Gowtham: Fani's only friend is Ezhil and Gowtham's only friend is Chandran, so it must be Dhinesh. Then Amudha's strangers are Bharatan, Chandran, Fani, Gowtham, and the remaining relations follow from the counts in the table.

Person

Friends

Acquaintances

Strangers

Amudha

Ezhil

Dhinesh

Bharatan, Chandran, Fani, Gowtham

Bharatan

Dhinesh

Ezhil

Amudha, Chandran, Fani, Gowtham

Chandran

Gowtham

Fani

Amudha, Bharatan, Dhinesh, Ezhil

Dhinesh

Bharatan, Ezhil

Amudha, Gowtham

Chandran, Fani

Ezhil

Amudha, Dhinesh, Fani

Bharatan, Gowtham

Chandran

Fani

Ezhil

Chandran, Gowtham

Amudha, Bharatan, Dhinesh

Gowtham

Chandran

Dhinesh, Ezhil, Fani

Amudha, Bharatan

This question

Friends of Ezhil: Amudha, Dhinesh, Fani. Friends of these (excluding Ezhil): Amudha – none else; Dhinesh – Bharatan; Fani – none else. People who are a friend or friend-of-a-friend: Amudha, Dhinesh, Fani, Bharatan = 4.

Hence, the answer is 4.

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