Key Concepts & Formulas

10 Practice MCQs

Q1. Pointing to a man, Sunita said, “He is the son of my father’s only son”. How is the man related to Sunita? A) Brother B) Son C) Cousin D) Nephew

Answer: B) Son

Solution:

• My father’s only son = My brother OR myself (if I’m male)
• Since Sunita is female (name), my father’s only son = my brother
• Son of my brother = my son

Shortcut: “Father’s only son” = “My son” (if speaker is mother)

Concept: Blood Relations - Direct relationship identification

Q2. If A is the brother of B; B is the sister of C; and C is the father of D, how is A related to D? A) Uncle B) Father C) Brother D) Grandfather

Answer: A) Uncle

Solution:

• A → Brother → B → Sister → C → Father → D
• A and C are siblings
• A is brother of D’s father = Uncle

Shortcut: Sibling of parent = Uncle/Aunt

Concept: Blood Relations - Chain relationships

Q3. A train driver’s wife is the daughter of your mother’s only brother. How are you related to the train driver? A) Son B) Nephew C) Brother-in-law D) Son-in-law

Answer: D) Son-in-law

Solution:

• Your mother’s only brother = Your maternal uncle
• His daughter = Your cousin sister
• Train driver married to your cousin sister = Your brother-in-law
• You are his son-in-law (married to his daughter)

Shortcut: Spouse of cousin = Brother/Sister-in-law

Concept: Blood Relations - In-law relationships

Q4. In a railway colony, P is the mother of Q; R is the brother of Q; S is the father of R. How is P related to S? A) Wife B) Sister C) Daughter D) Mother

Answer: A) Wife

Solution:

• P → Mother → Q
• R → Brother → Q (same parents)
• Therefore, P is mother of R
• S is father of R
• P and S are parents of R = Husband and Wife

Shortcut: Common child = Husband-Wife relationship

Concept: Blood Relations - Parental relationships

Q5. A station master said, “She is the daughter of my grandmother’s only child”. How is the girl related to the station master? A) Sister B) Daughter C) Niece D) Aunt

Answer: A) Sister

Solution:

• My grandmother’s only child = My parent (father/mother)
• Daughter of my parent = My sister

Shortcut: “Grandmother’s only child” = “My parent”

Concept: Blood Relations - Single child relationships

Q6. In a train crew, X and Y are brothers; R is the father of X; S is the sister of Y’s mother. How is S related to R? A) Wife B) Sister C) Sister-in-law D) Mother

Answer: C) Sister-in-law

Solution:

• X and Y are brothers → Same parents
• R is father of X → R is father of Y
• Y’s mother = R’s wife
• S is sister of Y’s mother = Sister of R’s wife
• Sister of wife = Sister-in-law

Shortcut: Sibling of spouse = Sister/Brother-in-law

Concept: Blood Relations - Extended in-law relationships

Q7. A railway employee said, “The man’s mother is my mother’s only daughter-in-law”. How is the railway employee related to the man? A) Father B) Uncle C) Grandfather D) Brother

Answer: A) Father

Solution:

• My mother’s only daughter-in-law = My wife
• Man’s mother = My wife
• Therefore, I am the man’s father

Shortcut: “Mother’s daughter-in-law” = “My wife”

Concept: Blood Relations - Generation gap analysis

Q8. In a railway family, A is the father of B, but B is not A’s son. C is the daughter of B and wife of D. E is the brother of C’s mother. How is E related to D? A) Father-in-law B) Brother-in-law C) Uncle D) Grandfather

Answer: B) Brother-in-law

Solution:

• A is father of B, but B is not son = B is daughter
• C is daughter of B = Granddaughter of A
• E is brother of C’s mother (B) = Brother of B
• D is married to C, so D is son-in-law of B
• E is brother of B = Brother-in-law of D

Shortcut: Brother of spouse’s parent = Uncle, but here it’s brother-in-law

Concept: Blood Relations - Complex gender identification

Q9. A train guard has 3 children. The guard’s son is the father of X, who is the nephew of Y, who is the guard’s daughter. How is Y related to X? A) Aunt B) Mother C) Sister D) Cousin

Answer: A) Aunt

Solution:

• Guard’s son = Father of X
• X is nephew of Y → Y is aunt/uncle of X
• Y is guard’s daughter = Sister of X’s father
• Therefore, Y is aunt of X

Shortcut: Nephew relationship → Aunt/Uncle relationship

Concept: Blood Relations - Nephew-niece relationships

Q10. In a railway workshop family, P’s father’s only sister’s only son is Q. Q’s mother’s only brother’s wife is R. R’s only daughter’s husband is S. How is S related to P? A) Brother-in-law B) Uncle C) Cousin D) No relation

Answer: A) Brother-in-law

Solution:

• P’s father’s only sister = P’s aunt
• Her only son Q = P’s cousin brother
• Q’s mother’s only brother = Q’s maternal uncle
• His wife R = Q’s aunt
• R’s only daughter = Q’s cousin sister
• Her husband S = Q’s brother-in-law
• S is also P’s brother-in-law (married to P’s cousin sister)

Shortcut: Trace through each relationship step-by-step

Concept: Blood Relations - Multiple generation chain

5 Previous Year Questions

PYQ 1. Pointing to a photograph, a railway TC said, “She is the daughter of my grandfather’s only son”. How is the man related to the girl? RRB NTPC 2021 CBT-1

Answer: Brother

Solution:

• My grandfather’s only son = My father
• Daughter of my father = My sister
• Therefore, man is brother of the girl

Exam Tip: “Only son” always means single child - no brothers

PYQ 2. A is B’s sister. C is B’s mother. D is C’s father. E is D’s mother. How is A related to D? RRB Group D 2022

Answer: Granddaughter

Solution:

• A → Sister → B
• C → Mother → B (and A)
• D → Father → C
• E → Mother → D
• A is child of C, C is child of D
• A is granddaughter of D

Exam Tip: Draw vertical family tree for clarity

PYQ 3. If X is the brother of the son of Y’s son, how is X related to Y? RRB ALP 2018

Answer: Grandson

Solution:

• Y’s son = Son of Y
• Son of Y’s son = Grandson of Y
• Brother of grandson = Another grandson
• X is grandson of Y

Exam Tip: Work backwards from the relationship

PYQ 4. A railway engineer has no brothers. His mother is the daughter of X. X is the husband of Y. Y is the grandmother of the engineer. How is X related to the engineer? RRB JE 2019

Answer: Maternal grandfather

Solution:

• Engineer has no brothers → Only child or has sisters
• Mother is daughter of X → X is maternal grandfather
• X is husband of Y → Y is grandmother
• X is maternal grandfather of engineer

Exam Tip: “No brothers” confirms maternal/paternal line

PYQ 5. In a railway station, P is the father of Q but Q is not his son. R is the spouse of P. S is the brother of Q. T is the sister of S. How is T related to R? RPF SI 2019

Answer: Daughter

Solution:

• P is father of Q, Q is not son = Q is daughter
• R is spouse of P = Mother of Q
• S is brother of Q = Son of P and R
• T is sister of S = Daughter of P and R
• T is daughter of R

Exam Tip: Gender clues (“not his son”) are crucial

Speed Tricks & Shortcuts

Common Mistakes to Avoid

Quick Revision Flashcards

Topic Connections

• Direct Link: Seating Arrangement - Family members sitting in order
• Combined Questions: Puzzle Test - Blood relations mixed with age/occupation
• Foundation For: Data Sufficiency - Determining relationships from given clues