Episode 8 — Aptitude and Reasoning / 8.21 — Blood Relation
8.21.c Solved Examples -- Blood Relation
Example 1: Basic Photograph Problem
Problem: Pointing to a photograph, Arun says, "He is the son of my father's only son." How is the person in the photograph related to Arun?
Solution:
Step 1: Arun's father's only son = Arun himself (since Arun is the only son).
Step 2: Son of Arun = Arun's son.
Arun's Father
|
Arun (only son)
|
[Person in photo] = Arun's Son
Answer: The person is Arun's son.
Example 2: Mother's Side Tracing
Problem: If A is B's sister, C is B's mother, D is C's father, E is D's mother, then how is A related to D?
Solution:
Step 1: Build the family tree.
E (F) (D's mother)
|
D (M) (C's father)
|
C (F) (B's mother)
|
+---+---+
| |
B (?) A (F) (A is B's sister)
Step 2: A is C's daughter. C is D's daughter. So A is D's granddaughter.
Answer: A is D's granddaughter.
Example 3: "Only" Keyword
Problem: Pointing to a lady, Ravi says, "She is the daughter of the only child of my grandmother." How is the lady related to Ravi?
Solution:
Step 1: Ravi's grandmother has only one child = Ravi's parent (father or mother).
Step 2: Daughter of Ravi's parent = Ravi's sister.
Grandmother
|
Only Child (Ravi's parent)
|
+---+---+
| |
Ravi [Lady] = Ravi's Sister
Answer: The lady is Ravi's sister.
Example 4: Complex Chain
Problem: A's mother is the sister of B's father. B's father's mother is C. How is C related to A?
Solution:
Step 1: A's mother is sister of B's father -> they are siblings.
Step 2: B's father's mother is C -> C is the mother of B's father.
Step 3: Since A's mother and B's father are siblings, they share the same mother = C.
C (F)
|
+------+------+
| |
B's Father (M) A's Mother (F)
| |
B A
Step 4: C is the mother of A's mother = A's maternal grandmother.
Answer: C is A's maternal grandmother.
Example 5: Coded Relationship
Problem: If A + B means "A is the father of B," A - B means "A is the wife of B," and A * B means "A is the brother of B," then what does P + Q - R mean?
Solution:
Step 1: Decode step by step.
- P + Q: P is the father of Q
- Q - R: Q is the wife of R
Step 2: Build the tree.
P (M) = Q's father
|
Q (F) ==== R (M) (Q is wife of R)
Step 3: P is the father of Q, and Q is the wife of R. So P is R's father-in-law.
Answer: P is the father-in-law of R.
Example 6: Multiple Relationships
Problem: A and B are brothers. C is B's father. D is C's sister. E is D's mother. How is B related to E?
Solution:
E (F)
|
+---+---+
| |
C (M) D (F) (C and D are siblings, E is their mother)
|
+---+---+
| |
A (M) B (M) (A and B are brothers, C is their father)
B is C's son. C is E's son. So B is E's grandson.
Answer: B is E's grandson.
Example 7: Pointing Problem with Gender Trap
Problem: Looking at a portrait, Sita says, "This person's mother is the mother-in-law of my husband." How is the person in the portrait related to Sita?
Solution:
Step 1: Sita's husband's mother-in-law = Sita's mother (because Sita is married to her husband, so Sita's mother is the husband's mother-in-law).
Step 2: The person's mother = Sita's mother.
Step 3: The person is Sita's sibling (brother or sister).
Sita's Mother ==== Sita's Father
|
+----+----+
| |
Sita [Person in portrait] = Sita's Sibling
Answer: The person is Sita's brother or sister.
Example 8: In-Law Relationships
Problem: A is married to B. C is B's brother. D is C's father. How is A related to D?
Solution:
D (M)
|
+---+---+
| |
B (?) C (M) (B and C are siblings, D is their father)
|
==== A (A is married to B)
A is married to D's child (B). So A is D's son-in-law or daughter-in-law (depending on A's gender).
Answer: A is D's son-in-law or daughter-in-law.
Example 9: Tricky "Father's Only Son"
Problem: Pointing to a man, a woman says, "His mother is the only daughter of my mother." How is the woman related to the man?
Solution:
Step 1: "Only daughter of my mother" = the woman herself (she is her mother's only daughter).
Step 2: The man's mother = the woman herself.
Step 3: The woman is the man's mother.
Woman's Mother
|
Woman (only daughter)
|
[Man] = Woman's Son
Answer: The woman is the man's mother.
Example 10: Reverse Tracing
Problem: If "A is the father of B" and "B is not A's son," how is B related to A?
Solution:
Step 1: A is B's father -> B is A's child.
Step 2: B is NOT A's son -> B must be A's daughter.
Answer: B is A's daughter.
Example 11: Five-Person Family
Problem: In a family of 5 members: P is Q's son. Q is R's mother. R is S's father. T is Q's husband. How is T related to R?
Solution:
T (M) ==== Q (F) (T is Q's husband)
|
+---+---+
| |
P (M) R (M)?
Wait -- Q is R's mother, and P is Q's son. So both P and R are Q's children.
T (M) ==== Q (F)
|
+------+------+
| |
P (M) R (M) (R is S's father -> R is male)
|
S (?)
T is Q's husband. Q is R's mother. So T is R's father.
Answer: T is R's father.
Example 12: Grandfather Determination
Problem: A says to B, "Your mother's husband's sister is my aunt." How is A related to B?
Solution:
Step 1: B's mother's husband = B's father.
Step 2: B's father's sister = B's paternal aunt.
Step 3: This aunt is also A's aunt -> A and B share the same paternal aunt.
Step 4: This means A and B's fathers are brothers, OR A and B are siblings.
Most likely: A and B are siblings or cousins (through paternal side).
Grandfather
|
+---+---+
| |
B's Father Aunt (sister)
|
+---+---+
| |
A B (if siblings)
Answer: A is B's brother or sister (sibling) or cousin.
Example 13: Coded Problem -- Multiple Codes
Problem: Given: A $ B means "A is the mother of B," A # B means "A is the father of B," A @ B means "A is the sister of B," A & B means "A is the brother of B." What is the relationship in P # Q @ R?
Solution:
Step 1: P # Q -> P is the father of Q.
Step 2: Q @ R -> Q is the sister of R.
Step 3: P is the father of Q, and Q is the sister of R -> Q and R are siblings -> P is also the father of R.
P (M)
|
+---+---+
| |
Q (F) R (?) (Q is sister, so Q is female)
Answer: P is the father of R.
Example 14: In-Law Chain
Problem: Rani's brother's wife's sister's husband is Anil. How is Anil related to Rani?
Solution:
Step 1: Rani's brother = X (male).
Step 2: X's wife = Y (female).
Step 3: Y's sister = Z (female).
Step 4: Z's husband = Anil.
Rani --- X (brother) ==== Y (wife)
|
Y's Sister = Z ==== Anil
Anil is the husband of the sister of Rani's brother's wife. There is no direct blood relation between Anil and Rani. Anil is connected through two marriages.
Answer: No direct blood relation. Anil is the husband of Rani's sister-in-law's sister (a distant relation through marriage).
Example 15: Generation Gap Problem
Problem: If X is Y's brother, Y is Z's father, Z is W's brother, and W is V's daughter, how is X related to V?
Solution:
? ==== V (F) (W is V's daughter -> V is W's parent)
|
+-----+-----+
| |
Z (M) W (F) (Z is W's brother)
Wait. Let me re-read: Y is Z's father. Z is W's brother. W is V's daughter.
Y (M)
|
+---+---+
| |
Z (M) W (F) (Z and W are siblings, Y is their father)
And V is W's mother (since W is V's daughter -> V is W's parent, and since Y is already W's father, V must be W's mother):
Y (M) ==== V (F)
|
+----+----+
| |
Z (M) W (F)
X is Y's brother:
+---+---+
| |
X (M) Y (M) ==== V (F)
|
+----+----+
| |
Z (M) W (F)
X is V's brother-in-law (husband's brother).
Answer: X is V's brother-in-law.
Example 16: "Introducing" Format
Problem: Introducing a girl, Rohan says, "She is the only daughter of the father of my sister's brother." How is the girl related to Rohan?
Solution:
Step 1: Rohan's sister's brother = Rohan himself (or another brother, but simplest case = Rohan).
Step 2: Father of Rohan = Rohan's father.
Step 3: Only daughter of Rohan's father = Rohan's sister.
Rohan's Father
|
+---+---+
| |
Rohan [Girl] = only daughter = Rohan's Sister
Answer: The girl is Rohan's sister.
Example 17: Negative Information
Problem: A and B are children of C. If A is not B's brother, how is A related to B?
Solution:
Step 1: A and B are siblings (children of C).
Step 2: A is NOT B's brother -> A is not male relative to B.
Step 3: A is B's sister (A is female).
Answer: A is B's sister.
Example 18: Multi-Generation Puzzle
Problem: There are 6 people in a family: P, Q, R, S, T, U. P and Q are married. R is the son of P. S is the daughter of Q. T is the brother of R. U is the mother of P.
Solution:
U (F) (U is P's mother)
|
P (?) ==== Q (?) (P and Q are married)
|
+------+------+
| | |
R (M) S (F) T (M) (R is P's son, S is Q's daughter, T is R's brother)
Since P and Q are married, R, S, and T are their children.
Relationships:
- U is the grandmother of R, S, and T.
- P and Q are parents.
- R, S, T are siblings.
- T is S's brother.
Answer: Complete family tree as shown above.
Example 19: Circular Clue Problem
Problem: A says to B, "Your father is my father's son." How is A related to B?
Solution:
Step 1: B's father = A's father's son.
Step 2: A's father's son = A himself (or A's brother).
Case 1: B's father = A -> A is B's father.
Case 2: B's father = A's brother -> A is B's uncle.
Case 1: Case 2:
A's Father A's Father
| |
A +-----+-----+
| | |
B A B's Father
|
B
Answer: A is either B's father or B's uncle.
Example 20: "Husband's Mother" Chain
Problem: Pointing to a lady, Ramesh says, "She is the daughter of my grandfather's only child." How is the lady related to Ramesh?
Solution:
Step 1: Ramesh's grandfather's only child = Ramesh's father (or mother -- only child means one child).
Step 2: If the only child is Ramesh's father: daughter of Ramesh's father = Ramesh's sister.
Step 3: If the only child is Ramesh's mother (maternal grandfather): daughter of Ramesh's mother = Ramesh's sister or Ramesh himself if female.
Grandfather
|
Only Child
|
[Lady] = sister of Ramesh (most likely answer)
Answer: The lady is Ramesh's sister.
Example 21: Married Couple Identification
Problem: In a family, A is B's husband, C is D's wife, A is C's father, and E is B's son. How is D related to E?
Solution:
A (M) ==== B (F) (A is B's husband)
|
C (F) ==== D (M) (C is D's wife, A is C's father)
|
...
Wait -- E is B's son. So:
A (M) ==== B (F)
|
+------+------+
| |
C (F)====D(M) E (M) (C and E are siblings)
D is married to C. E is C's brother. So D is E's brother-in-law (sister's husband).
Answer: D is E's brother-in-law.
Example 22: Three-Generation Problem
Problem: X's mother is Y's daughter. Z is Y's husband. W is X's father. How is W related to Z?
Solution:
Step 1: X's mother is Y's daughter -> Y is X's maternal grandmother.
Step 2: Z is Y's husband -> Z is X's maternal grandfather.
Step 3: W is X's father.
Z (M) ==== Y (F) (Z and Y are married)
|
X's Mother (F) ==== W (M) (X's parents)
|
X
W is married to Z's daughter -> W is Z's son-in-law.
Answer: W is Z's son-in-law.
Example 23: "Only Daughter-in-law"
Problem: Pointing to a woman, Anil says, "She is my father's only daughter-in-law's sister." How is the woman related to Anil?
Solution:
Step 1: Anil's father's only daughter-in-law = Anil's wife (assuming Anil is the only son, or the wife of the only married son).
Most commonly: Anil's father's daughter-in-law = Anil's wife.
Step 2: Anil's wife's sister = the woman.
Anil's Father
|
Anil ==== Anil's Wife
|
Wife's Sister = [Woman]
Answer: The woman is Anil's sister-in-law (wife's sister).
Example 24: Puzzle-Based Family (5 clues)
Problem: In a family of 5: (1) M is N's husband. (2) O is the only son of M. (3) P is O's sister. (4) Q is M's mother-in-law. How is Q related to O?
Solution:
Clue 1: M (M) ==== N (F)
Clue 2: O (M) is M and N's only son
Clue 3: P (F) is O's sister -> also M and N's daughter
Clue 4: Q is M's mother-in-law -> Q is N's mother
Family Tree:
Q (F)
|
N (F) ==== M (M)
|
+----+----+
| |
O (M) P (F)
Q is N's mother. N is O's mother. So Q is O's maternal grandmother.
Answer: Q is O's maternal grandmother (grandmother).
Example 25: Double In-Law
Problem: A's son is B's brother-in-law. How is A related to B?
Solution:
Step 1: A's son is B's brother-in-law.
Step 2: Brother-in-law can mean:
- (a) Husband's brother, OR
- (b) Wife's brother, OR
- (c) Sister's husband
Case (a): A's son is B's husband's brother -> B's husband and A's son are brothers -> A is B's father-in-law.
Case (b): A's son is B's wife's brother -> B's wife is A's daughter -> A is B's father-in-law.
Case (c): A's son is B's sister's husband -> A's son married B's sister -> A is the father of B's sister's husband.
Most common interpretation: A is B's father-in-law (cases a and b).
Answer: A is B's father-in-law (most likely).
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