Chapter Summary: Blood Relations | Logical Reasoning (LR) and Data Interpretation (DI) - CAT PDF Download

Introduction to Blood Relations

Blood relation questions test your ability to understand and analyze familial relationships using logical reasoning. These questions often involve identifying relationships between individuals based on given clues, which may be direct or indirect. The key is to systematically break down the information and represent it visually, typically using family trees.

Key Concepts

• Direct Clues: Explicit statements like "Emily likes Coke" or "Deepak is the father of Fatima."
• Indirect Clues: Implied relationships, e.g., "Deepak does not like Thums Up or Pepsi," requiring logical deduction.
• Family Tree Representation: A multilevel diagram where:
  • Males and females are marked distinctly (e.g., circles for females, rectangles for males).
  • Generations are represented vertically, and siblings are on the same level.
  • Marital relationships are shown with horizontal lines, and parent-child relationships with vertical lines.
• Common Relationships:
  • Mother/Father: Parent of a child.
  • Son/Daughter: Child of a parent.
  • Brother/Sister: Siblings (same parents).
  • Husband/Wife: Married couple.
  • In-laws: Relationships through marriage (e.g., mother-in-law, brother-in-law).
• Additional Information: Likes, dislikes, or preferences (e.g., "Emily likes Coke") can help identify individuals in the family tree.

Tips for Solving Blood Relation Questions

1. Start with Direct Clues: Identify clear relationships first (e.g., "Deepak is the father of Fatima").
2. Build a Family Tree: Use a diagram to map relationships, ensuring clarity in generations and connections.
3. Mark Genders and Generations:
   • Use symbols to differentiate males and females.
   • Place siblings on the same level and parents above children.
4. Use Indirect Clues for Deduction:
   • Eliminate possibilities (e.g., "Deepak does not like Thums Up or Pepsi" means he likes the remaining options).
   • Cross-reference with family tree positions.
5. Focus on Key Individuals: Start with individuals mentioned in multiple clues to anchor the family tree.
6. Combine Diagrams if Needed: If multiple diagrams are given (e.g., couple and siblings), merge them logically.
7. Revisit for Consistency: Ensure all clues align with the constructed family tree.

Solved Examples

The following examples are solved using the clues and illustrations provided in the document.

Illustration 1: Family of Six Persons

• Clues:
  • Family of six: Abhay, Bantu, Cathy, Deepak, Emily, Fatima (three males, three females; two married couples, two unmarried).
  • Emily likes Coke, mother-in-law of Abhay (wife of Cathy). Deepak is the father of Fatima.
  • Cathy does not like Thums Up or Pepsi. Bantu likes Limca, sister of Fatima (who likes Sprite).
  • Deepak does not like Thums Up or Pepsi, so he likes Fanta (since Emily likes Coke).

Q1: Who among the following likes Thums Up?
Sol:

• Deepak is the father of Fatima (Deepak: male, Fatima: female).
• Abhay, Bantu, Cathy are siblings; Emily is their mother (mother-in-law of Abhay means wife of Cathy).
• Cathy (male, married to Emily) and Deepak (male, father of Fatima) are the two married males.
• Bantu (female, sister of Fatima) and Fatima (female) are unmarried.
• Remaining person: Abhay (male, unmarried).
• Likes: Emily (Coke), Deepak (Fanta), Cathy (not Thums Up or Pepsi, so Limca or Sprite), Bantu (Limca), Fatima (Sprite).
• Cathy must like Sprite (since Bantu likes Limca). Abhay likes Thums Up (remaining option).

Ans: Abhay (a) likes Thums Up.

Q2: How is Fatima related to Emily?
Sol:

• Deepak (father of Fatima) is married to Emily (since Cathy is married to Emily, Deepak must be the other married male).
• Emily is Fatima’s mother.

Ans: Daughter (d).

Q3: One of the married couple is:
Sol:

• From the family tree: Deepak (father) and Emily (mother) are a married couple.

Answer: Deepak-Emily (b).

Q4: Which of the following cold drinks is liked by Abhay?
Sol:

• From Question 1, Abhay likes Thums Up.

Ans: Thums Up (a).

Q5: How many sons does Emily have?
Sol:

• Emily’s children: Cathy (male), Abhay (male), Bantu (female). Fatima is also her daughter (via Deepak).
• Sons: Cathy and Abhay.

Ans: Two (c).

Example 1 (Statement-Based)
Statement: "Ralf said, ‘His mother is the only daughter of my mother-in-law.’ How is Ralf related to the boy?"
Solution:

• Ralf’s mother-in-law has one daughter (Ralf’s wife). The boy’s mother is this daughter, so Ralf is the boy’s father.

Ans: Father (d).

Example 2 (Statement-Based)
Statement: Pointing to a man in a photograph, a woman said, “His brother’s father is the only son of my grandfather.” How is the woman related to the man in the photograph?

Sol:

• The man’s brother’s father is the man himself (only son of the woman’s grandfather). The woman is the man’s sister.

Ans: Sister (d).

Example 3 (Statement-Based)
Statement: If Nina says, “Anna’s father Rick is the only son of my father-in-law Mick.” Then how is Bridgette, who is the sister of Anna, related to Mick?
Sol:

• Rick (Anna’s father) is the only son of Mick. Bridgette (Anna’s sister) is Rick’s daughter, so Mick’s granddaughter.

Ans: Daughter (since “daughter” here refers to granddaughter in the context of Mick).

Example 4 (Symbolic)
Statement: "X – Y" means "X is the father of Y"; "X × Y" means "X is the wife of Y"; "X + Y" means "X is the sister of Y". On the basis of this information, what does X + Y – Z mean?
Solution:

• X + Y: X is the sister of Y (X and Y are siblings, likely female).
• Y – Z: Y is the father of Z.
• X (female) is the sister of Y (male), and Y is the father of Z. So, X is the aunt of Z.

Answer: Sister (of Y, who is the father of Z).

Tips and Tricks Table

The following table summarizes key strategies for solving blood relation questions efficiently:

This summary sheet provides a comprehensive guide for CAT aspirants to tackle blood relation questions, with practical examples and actionable tips.